January 22, 2025

What is RAG: Definition, use cases, and how to implement it

Retrieval-Augmented Generation is a transformative approach to building smarter, dynamic AI systems. A practical guide along with an example implementation.

Picture this: You’re at a sprawling library filled with countless books, documents, and journals. You have a question that needs answering, but you don’t have the time to sift through the shelves. Luckily, the librarian is a genius—they quickly fetch the most relevant books and even summarize the answer for you. Efficient, right?

This is how Retrieval-Augmented Generation (RAG) works. Think of RAG as the AI equivalent of that brilliant librarian who doesn’t just know where to look for answers but also crafts a coherent response tailored to your needs. RAG combines two powerful processes: retrieving relevant information from external sources and generating responses based on that information.


What is RAG?


What’s the big deal about RAG?

Let’s say you’re using a chatbot powered by a large language model (LLM). While the model is highly intelligent and creative, it has a limitation: it only knows what it was trained on. Its knowledge is static and limited to data that existed up to a specific point in time. If you ask it about recent developments, niche topics, or highly specific information, it might fumble.

RAG overcomes this by dynamically fetching relevant, up-to-date information from external knowledge sources, such as databases, documents, or APIs. This makes the system both more accurate and adaptable.

Have you ever used a chatbot or virtual assistant that gave outdated or incomplete information? Imagine how much better it could be if it could search for and incorporate current, relevant data in real-time!


Breaking Down the Magic of RAG

To understand RAG, we need to look at its two core components: retrieval and generation.

High-Level Overview

At a basic level, RAG works like this:

Retrieval: When you ask a question, the system searches through a connected knowledge base—like a collection of documents, articles, or a database—and fetches the most relevant pieces of information.

Generation: The retrieved information is passed to a language model, which uses it to generate a detailed, coherent response.

This combination enables RAG to provide contextually rich answers that are informed by the latest or domain-specific knowledge.

Deeper Dive

From a technical perspective, RAG combines two types of AI models:

Retriever: A system that identifies the most relevant pieces of information based on your query. It uses techniques like vector embeddings, where text is represented as numerical vectors to measure similarity.

Generator: A language model (such as GPT) that takes the retrieved information and crafts a fluent response tailored to your query.

For example:

The retriever might identify two documents about "RAG in AI" from a database of thousands.

The generator then uses these documents as context to answer your question: “What is RAG?

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