AI & Machine Learning Cheat Sheet: Key Models, Use Cases & When to Use Them
Updated on Apr 02, 2025 | 28 min read | 7.8k views
Share:
For working professionals
For fresh graduates
More
Updated on Apr 02, 2025 | 28 min read | 7.8k views
Share:
Table of Contents
Latest Update: The worldwide Artificial Intelligence market size is projected to grow to ₹1,09,80,620 crore by 2030, at a CAGR of 37.3% from 2023 to 2030.
As an AI professional, you have to pick the right AI or ML algorithm for different tasks. This can be overwhelming with so many options available. That’s where an AI cheat sheet comes in. It’s designed to help you quickly understand the most popular algorithms, like Decision Trees, SVMs, and Neural Networks, and know exactly when and how to use them.
This machine learning cheat sheet will guide you in making the right choice for your project. Get the insights you need, fast, and streamline your workflow with ease!
AI and ML algorithms are the foundational models that power intelligent systems. AI algorithms help machines make decisions or predictions based on input data. ML algorithms focus specifically on enabling machines to learn patterns from data, adapt, and improve over time.
In this AI cheat sheet, we’ll be breaking down AI systems into two broad categories:
1. Rule-Based Systems: These systems follow a predefined set of rules to make decisions. While they are effective for structured tasks, they lack the ability to adapt to new data. Commonly used in expert systems and simple decision-making models.
2. Learning-Based Systems: This category includes ML algorithms, which learn patterns from data and improve over time. They can be further broken down into:
Selecting the right algorithm is crucial for the success of any AI/ML project. The chosen algorithm must fit the problem at hand while balancing accuracy, interpretability, and computational cost.
Did you know? For fraud detection in banking, a Random Forest model might be used for its ability to handle complex, high-dimensional data while providing high accuracy.
In customer segmentation, K-Means Clustering would be ideal. It helps identify distinct customer groups based on purchasing behavior without needing labeled data.
Here’s a comparison of common ML algorithms based on interpretability and computational cost:
Algorithm |
Interpretability |
Computational Cost |
Decision Trees | High | Low |
Random Forests | Medium | Medium |
Neural Networks | Low | High |
K-Nearest Neighbors | High | Medium |
Logistic Regression | High | Low |
Also Read: Career Opportunities in Artificial Intelligence in 2025
Why Should You Learn AI Algorithms? AI algorithms can solve complex challenges that traditional systems can’t. As the demand for AI talent increases, millions of AI-related roles are opening up in the market. There is an immense opportunity for professionals like you to enter the field.
Next in this machine learning cheat sheet, let’s understand the core types of AI and ML algorithms.
AI and ML algorithms are the engines behind intelligent systems, helping machines learn from data and make decisions. To become an AI professional, it's important to understand the three primary categories of learning.
Each method mentioned in this machine learning algorithms cheat sheet has its unique strengths and applications, depending on the problem you're solving. Let's understand each category and explore when and how they work:
Supervised learning is like teaching a machine with labeled examples. For instance, in email spam detection, you provide the model with a dataset of emails labeled as "spam" or "not spam." The model learns to identify patterns in the email content, such as specific keywords or formatting. After training, it can predict whether new emails are spam based on these patterns, even if it hasn't seen them before.
How it Works? In supervised learning, the algorithm is trained using a dataset that contains both input-output pairs. The process involves several key steps:
Here are some of the common algorithms in supervised learning:
When it's Used:
Unsupervised learning works with data that has no labels. For example, in customer segmentation, the algorithm groups customers based on similarities in their purchasing behavior, without knowing in advance what those groups are. It identifies patterns or clusters within the data, helping businesses discover new insights, like identifying high-value customers or market segments.
How it Works? In unsupervised learning, the algorithm is given data without labels and tasked with finding hidden patterns. The process works as follows:
Common Algorithms:
When it's Used:
Reinforcement learning teaches machines to make decisions through trial and error. For example, in training a robot to navigate a maze, the robot interacts with the environment and receives rewards for correct moves and penalties for mistakes.
Over time, it learns the best path to take by maximizing rewards and minimizing penalties, making it ideal for tasks like game playing or autonomous driving, where decisions are made sequentially.
How it Works? In reinforcement learning, an agent learns to make decisions by interacting with an environment and receiving feedback. The process follows these key steps:
Common Algorithms:
When it's Used:
When selecting an algorithm for your AI or ML project, consider the problem you’re solving, the type of data you have, and the computational resources available. Each algorithm has strengths and weaknesses depending on the task at hand.
Now, let’s explore how you can choose the best models for your task.
Choosing the right algorithm in AI and ML projects depends on data size, problem complexity, and specific objectives. For instance, Neural Networks or CNNs are ideal for large, complex datasets like image recognition. Decision Trees or K-Means work better for simpler tasks like customer segmentation.
This section provides insights on when and why to use each algorithm, helping you balance accuracy, speed, and interpretability based on real-world considerations.
Here’s a table comparing the popular models:
Model |
Accuracy |
Speed |
Dataset Size |
Linear Regression | Medium | Fast | Small to Medium |
Decision Trees | Medium to High | Medium | Medium to Large |
Logistic Regression | Medium | Fast | Small to Medium |
Support Vector Machine (SVM) | High | Slow | Medium to Large |
Neural Networks | Very High | Slow | Large |
Random Forest | High | Medium | Medium to Large |
K-Means | Medium | Fast | Small to Medium |
Hierarchical Clustering | Medium | Medium to Slow | Small to Medium |
When it comes to predictive tasks, Linear Regression and Decision Trees are two of the most commonly used algorithms, but they excel in different areas.
Here’s when to use them and why:
Algorithm |
When to Use |
Example |
Linear Regression | Best for continuous output prediction where relationships are linear. | Predicting sales revenue based on historical data like past sales and marketing spend. |
Decision Trees | Ideal for both classification and regression with non-linear relationships. | Assessing customer risk levels based on attributes like credit score, transaction history, etc. |
Key Insight: Linear Regression is fast, simple, and interpretable but struggles with non-linear relationships and outliers. Decision Trees can capture more complexity and handle non-linear relationships well, but they are prone to overfitting and can be computationally expensive.
Logistic Regression and Support Vector Machines (SVM) are both powerful classification algorithms, but each excels in different scenarios.
Here’s when to use them and why:
Algorithm |
When to Use |
Example |
Logistic Regression | Best for binary classification with a linear decision boundary. | Predicting whether an email is spam or not based on features like word frequency. |
Support Vector Machine (SVM) | Ideal for classification tasks where the data is not linearly separable or when high accuracy is needed. | Classifying images of handwritten digits (0-9) or identifying whether an image is of a cat or dog. |
Key Insight: Logistic Regression is simple, fast, and highly interpretable but may not perform well on complex datasets with overlapping classes. SVM is highly accurate and works well with complex datasets, especially in high-dimensional spaces. However, it’s computationally expensive and can be slow with large datasets.
Both Neural Networks and Random Forest are powerful but serve different purposes based on complexity and interpretability.
Neural Networks are ideal for large, unstructured data like medical image analysis. CNNs can detect intricate patterns in images, such as identifying tumors. Random Forests may miss these due to data complexity. Despite their higher computational cost, Neural Networks excel in these tasks.
Random Forests, however, are preferred when interpretability and quick deployment are essential, such as in financial risk assessment or predictive maintenance. They offer good accuracy and transparency, making them easier to explain to stakeholders.
Here’s when to use them and why:
Algorithm |
When to Use |
Example |
Neural Networks | Best for tasks involving large amounts of data with complex patterns, such as image and speech recognition or natural language processing. | Recognizing objects in an image or translating text in real-time. |
Random Forest | Ideal for classification and regression tasks where interpretability and performance are crucial, and to avoid overfitting. | Predicting loan default risk based on customer data or classifying diseases from medical data. |
Key Insight: Neural Networks offer powerful accuracy, especially with large datasets, but they lack interpretability, making them difficult to explain. Random Forest provides high accuracy with better interpretability and is less prone to overfitting, making it a preferred choice for many real-world applications.
When it comes to clustering, K-Means and Hierarchical Clustering are two of the most commonly used techniques, but each has its strengths depending on the dataset.
Here’s the information formatted in a table:
Algorithm |
When to Use |
Example |
K-Means Clustering | Ideal when you know the number of clusters in advance and the data is large. | Segmenting customers into distinct groups based on purchasing behavior. |
Hierarchical Clustering | Best when you want to explore the data's hierarchical relationships and do not know the number of clusters beforehand. | Creating a taxonomy of species or grouping similar documents. |
Key Insight: K-Means is efficient for large datasets but requires you to define the number of clusters beforehand, which may not always be feasible. Hierarchical Clustering is more flexible and doesn’t require the number of clusters to be predefined, but it can be slower and less scalable for large datasets.
Evaluate your problem, data size, and complexity to make an informed decision and get the best results.
Also Read: How to Become an Artificial Intelligence Engineer? Salary, Skills & Steps
Next in the ML algorithms cheat sheet, let’s explore one of machine learning’s most popular subsets.
Deep learning is helping solve complex problems across industries, enabling machines to mimic human cognitive functions like vision, language understanding, and creativity.
Unlike traditional machine learning models, deep learning algorithms use neural networks with multiple layers to automatically extract features and learn patterns from large datasets.
These models are the foundation of some of the most advanced AI applications today, from autonomous vehicles to medical diagnostics.
Neural networks are the core structure behind deep learning models. These networks consist of layers of interconnected nodes, or "neurons," that transform input data into meaningful output.
Each layer processes the data, extracting features, and passing them on to the next layer for further refinement.
When to Use: Neural networks excel in problems where data is highly complex and unstructured, like image recognition or language translation.
How it Works?
Example: Neural networks are often used in self-driving cars, where they process data from cameras and sensors to recognize objects, pedestrians, and road signs.
The network continuously improves its accuracy over time by adjusting its weights through the vast amounts of training data.
Another example is predicting stock prices using past market data. The neural network learns to recognize patterns in historical stock data, and after extensive training, it can forecast future trends based on its learned relationships.
Convolutional Neural Networks (CNNs) are a type of deep learning architecture specifically designed for processing structured grid-like data, such as images.
CNNs have a unique architecture that includes convolutional layers, pooling layers, and fully connected layers. They can automatically extract and learn spatial hierarchies of features in images.
When to Use: Ideal for image classification, object detection, and facial recognition tasks.
How it Works?
Example: In medical imaging, CNNs are used to detect abnormalities such as tumors in X-rays or MRIs. The model can automatically identify patterns that may be too subtle for the human eye, offering faster and more accurate diagnoses.
In face recognition, CNNs process images to identify distinguishing facial features. As the network trains on a large dataset of faces, it becomes increasingly accurate at recognizing individuals based on key facial landmarks, like the eyes and mouth.
Recurrent Neural Networks (RNNs) are designed to process sequential data where the order of inputs matters, like time series data or text.
Unlike traditional neural networks, RNNs have loops that allow information to persist, making them suitable for tasks where previous data points influence current ones.
When to Use: Best for tasks involving time-series data, speech recognition, and natural language processing (NLP), where the sequence of data is essential.
How it Works?
Example: In text generation, RNNs can be used to create human-like language. For instance, given a sequence of words, the network learns the structure of the language, predicting the next word in a sentence based on previous words. Similarly, in stock price prediction, RNNs can analyze historical price data, taking past prices into account to predict future trends.
This is useful for forecasting market movements, where past data directly influences future outcomes.
Transformers have revolutionized the field of Natural Language Processing (NLP) by overcoming the limitations of RNNs. These models use self-attention mechanisms to weigh the importance of different words in a sentence, regardless of their position.
Unlike RNNs, which process data sequentially, transformers can analyze all input data at once, making them faster and more efficient.
When to Use: Ideal for tasks like text generation, translation, summarization, and sentiment analysis.
How it Works?
Transformers are designed to process sequential data in parallel rather than step-by-step, as seen in traditional RNNs. This is accomplished through the self-attention mechanism, which helps the model weigh the importance of different words in a sentence regardless of their position.
The transformer architecture processes the entire input sequence simultaneously, allowing it to capture long-range dependencies in the data, making it highly efficient for NLP tasks like translation and summarization.
The BERT (Bidirectional Encoder Representations from Transformers) model takes this a step further by reading text in both directions (left-to-right and right-to-left), giving it a deeper understanding of the context of each word. This allows BERT to better understand nuances in language, such as word ambiguity and sentence structure.
Example: BERT is widely used for question-answering systems. For instance, given a passage of text, BERT can understand the context and return accurate answers to specific queries.
It is also employed in sentiment analysis, where it can determine the sentiment behind a piece of text (positive, negative, or neutral). For example, BERT might be used to analyze customer feedback, automatically classifying it as positive or negative based on the context of the words used.
Generative Adversarial Networks (GANs) are a type of deep learning model that consists of two competing networks: the generator and the discriminator. The generator creates fake data, while the discriminator evaluates it.
The goal is for the generator to produce data so realistic that the discriminator cannot tell the difference.
When to Use: Ideal for generating synthetic data, enhancing images, or creating realistic simulations for training purposes.
How it Works? Generative Adversarial Networks (GANs) consist of two competing neural networks: the generator and the discriminator. The generator creates synthetic data, while the discriminator evaluates it.
The two networks are trained together in a process called adversarial training. The generator improves by trying to "fool" the discriminator into thinking the synthetic data is real.
The discriminator gets better at distinguishing between real and fake data. Over time, the generator produces more realistic data, and the discriminator becomes more adept at identifying it.
GANs are widely used for tasks that require generating new data, such as creating realistic images or synthesizing new music. The adversarial nature of the training process helps ensure that the generated data closely resembles real-world data.
Example: In artificial image generation, GANs can create realistic images of people, landscapes, or objects that don’t exist in the real world. This is useful for applications like creating synthetic datasets for training other machine learning models when real-world data is scarce or difficult to obtain.
In fashion, GANs are used to design new clothing items by generating novel designs based on existing trends and styles.
Did you Know? In healthcare, deep learning models have enhanced medical diagnosis accuracy by over 40% in recent years.
As deep learning models continue to evolve, learning these advanced architectures will be key to solving some of the most complex and impactful problems across industries.
Also Read: How To Improve Your Career Skills for a Better Job and Employability [2025]
Now that you’re familiar with the deep learning models, let’s look at some of the key factors to consider when using any AI or ML algorithms and models.
Choosing the right AI/ML algorithm isn’t just about complexity; it’s about aligning the model with your project’s specific needs. Factors like dataset size, quality, and available computational resources are crucial.
Small, high-quality datasets might work well with simpler models like Logistic Regression, while large datasets require more powerful models like Neural Networks.
However, businesses often face challenges such as limited data or computational power. To address this, techniques like data augmentation and transfer learning can help with data scarcity, while cloud computing can tackle resource limitations.
Understanding these factors ensures you choose the right model for your project, directly linking to earlier discussions on algorithm selection.
Let’s break down the factors you’ll encounter and how to make informed decisions based on your project’s needs.
You’ll face this factor early in your project. If you're working with limited data, a simple model might perform better due to the risk of overfitting with complex algorithms. Conversely, a large dataset gives you the freedom to use more sophisticated models, such as deep learning, which can process vast amounts of data and extract complex patterns.
How to Decide:
For example, if you’re working with a small dataset of customer feedback, a Decision Tree might be enough to classify sentiment. But, if you're analyzing millions of customer interactions, Deep Learning models could uncover deeper insights and handle the complexity.
This factor becomes especially important when your stakeholders require transparency, or when your model is used in a regulated industry like finance or healthcare, where explanations are critical.
Accuracy might be the top priority in tasks like image classification. Interpretability is more important in tasks like medical diagnosis, where the reasoning behind a decision needs to be clear.
How to Decide:
Decision Trees are ideal for loan approval systems due to their interpretability, helping explain how inputs like income or credit score influence decisions.
Computational requirements are crucial when you're dealing with large datasets or running real-time predictions. Complex models like Deep Learning require high computational power.
This can become a bottleneck if you don't have access to GPUs or a strong infrastructure. On the other hand, simpler models like Logistic Regression can run efficiently on typical computing hardware.
How to Decide:
For example, say you're building a real-time recommendation engine with limited infrastructure. You might use Random Forests due to their high accuracy and moderate computational requirements.
But, for advanced facial recognition, you'll likely need CNNs with GPU support to process high-resolution images quickly.
Real-time processing requirements play a crucial role in algorithm selection. For time-sensitive tasks like fraud detection or autonomous vehicles, low-latency models are essential. Deep Learning models, while highly accurate, can be slow in both training and inference, which could become a bottleneck.
For applications like speech-to-text with strict latency requirements, faster models like Decision Trees or SVM may be better suited. Conversely, tasks like predictive maintenance in manufacturing prioritize accuracy over speed, making more complex models like Random Forests or Neural Networks a good choice.
How to Decide:
In a real-time fraud detection system, you might choose SVMs or Random Forests for their faster processing time, while in image classification, where real-time performance is less critical, CNNs could be a better fit for their accuracy.
As your project grows, you may encounter scalability challenges. You need to think about how your chosen algorithm will scale with increasing data or evolving needs. For instance, Deep Learning models might work well in the lab but become cumbersome and resource-intensive when deployed at scale.
How to Decide:
If you’re working with a large-scale, evolving dataset, such as in real-time image classification, the deep learning model may be effective but will need frequent monitoring and updates.
If you’re building a personalized recommendation system for an e-commerce platform, you might choose Random Forests for their ease of deployment and scalability.
Deep Learning models may be more appropriate for highly dynamic systems. This can be a real-time video streaming service that requires continuous, complex data analysis.
Tailor your choice to fit the specific needs and constraints of your application, ensuring optimal performance and long-term success.
Also Read: Top 5 Machine Learning Models Explained For Beginners
Now that you have a fair idea of what model to choose for specific projects, let’s look at some of the future trends pertaining to AI and ML algorithms.
AI and Machine Learning are becoming more popular, with innovations like AutoML simplifying model deployment, and Explainable AI (XAI) bringing transparency in decision-making. Federated Learning is enabling privacy-preserving models, while Quantum Computing promises to accelerate AI training and solve complex problems.
These advancements will redefine how AI is applied, making it more efficient, accessible, and secure for businesses.
AutoML (Automated Machine Learning) is making it easier for developers to build AI models without needing deep expertise in machine learning. AutoML automates tasks like feature selection, model selection, and hyperparameter tuning, drastically reducing the time and effort required to create effective models.
What’s Happening? A significant percentage of AI models will incorporate AutoML techniques. It allows businesses and individuals to develop and deploy machine learning models more quickly and efficiently. This trend is democratizing AI, enabling teams with limited ML expertise to use it.
Example: If you’re working on a customer segmentation project, AutoML tools like Google Cloud AutoML can automatically select the best model and fine-tune it for you. This saves time on experimentation and optimizes your results.
Explainable AI (XAI) aims to make AI models, particularly complex ones like neural networks, more transparent and understandable. As AI models become more powerful, stakeholders demand greater clarity on how decisions are made. XAI is all about providing human-readable explanations of AI's decision-making process.
Why it Matters? XAI is crucial in industries like healthcare and finance, where understanding AI's reasoning is essential for trust and compliance. By 2025, more businesses will prioritize explainability, making AI decisions easier to understand and explain to non-technical stakeholders.
Example: In healthcare, an AI diagnosing diseases based on medical images can use XAI methods to show which parts of an image contributed to the diagnosis. This helps doctors trust and validate the model’s decision.
Federated learning is a decentralized approach where the model is trained across many devices without sharing sensitive data. Instead of sending data to a central server, data stays on the device, and only model updates are shared. This method enhances privacy and security, particularly important in fields like finance and healthcare.
Why it Matters? Federated learning is revolutionizing how AI is used in privacy-sensitive applications. It allows for the development of AI models without compromising user privacy, making it an ideal solution for industries handling sensitive data.
Example: In mobile health apps, federated learning can enable AI models to learn from user data on their devices (like fitness or health metrics) without uploading private information. This ensures privacy while still benefiting from personalized AI insights.
Also Read: Machine Learning Career Path: 12 In-Demand Roles, Skills, and Salary Insights
Quantum computing is set to accelerate AI by solving complex problems that classical computers can’t handle. By leveraging quantum bits (qubits), quantum computers can process large-scale computations at speeds unimaginable with current hardware. This could lead to breakthroughs in AI optimization, data analysis, and model training.
What’s Happening? Though still in its early stages, quantum computing has the potential to revolutionize AI by 2030, with significant advancements expected in machine learning algorithms. As quantum hardware improves, we’ll see AI models capable of solving previously intractable problems.
Example: Imagine optimizing a complex supply chain system using quantum computing to evaluate millions of possibilities in real time, enabling businesses to make decisions faster and more accurately.
Graph Neural Networks (GNNs) are a type of neural network designed to handle data that is structured as graphs. This is particularly useful for modeling complex relationships like social networks, molecules, or transportation systems.
Why it Matters? GNNs are gaining traction because they can model dependencies and interactions between entities in a way that traditional neural networks can’t. They’re expected to play a significant role in fields such as social network analysis, drug discovery, and recommendation systems.
Example: In drug discovery, GNNs can model the interactions between molecules, helping researchers identify new compounds for medical treatments. In social media, GNNs are used to understand user behavior by analyzing connections and interactions within the social graph.
As these trends evolve, staying ahead of the curve will be key to leveraging the next generation of AI technologies.
Also Read: Top 10 Best Machine Learning Courses: 2025 Edition
By 2025, it’s expected that a significant percentage of businesses will use AI-powered automation to streamline their operations. Focusing on continuous learning and upskilling is essential for career progression in the AI field.
AI and ML are experiencing explosive growth worldwide. Globally, the AI market is expected to reach INR 15,58,000 crore by 2025. Organizations are seeking data scientists with a good grasp of ML algorithms. From AutoML to deep learning models like CNNs and RNNs, knowing when to use these algorithms is a key skill for your career progression.
Now is the time to get into this field! Gain hands-on experience, earn certifications, and explore specialized courses in machine learning models and algorithms. Stay updated on the latest trends in AI.
Not sure where to begin? Connect with upGrad’s career counseling for personalized advice. You can also visit a nearby upGrad center for hands-on training to accelerate your AI journey.
Expand your expertise with the best resources available. Browse the programs below to find your ideal fit in Best Machine Learning and AI Courses Online.
Discover in-demand Machine Learning skills to expand your expertise. Explore the programs below to find the perfect fit for your goals.
Discover popular AI and ML blogs and free courses to deepen your expertise. Explore the programs below to find your perfect fit.
References:
https://economictimes.indiatimes.com/tech/artificial-intelligence/ai-jobs-command-premium-pay-as-companies-fill-specialised-roles/articleshow/111072613.cms?from=mdr
https://tateeda.com/blog/ai-powered-diagnostics-in-healthcare#:~:text=Precision%20in%20Analysis%3A%20AI%20has,where%20early%20diagnosis%20is%20critical.
https://www.marketsandmarkets.com/Market-Reports/artificial-intelligence-market-74851580.html
https://economictimes.indiatimes.com/jobs/hr-policies-trends/ai-job-market-booms-with-42-growth-over-two-years-overall-hiring-up-by-31-yoy-in-december-foundit/articleshow/117450802.cms?from=mdr
Get Free Consultation
By submitting, I accept the T&C and
Privacy Policy
Top Resources