AI Basics You MUST Understand Before Building AI Agent

Yisak Bule — Thu, 21 May 2026 22:55:00 +0000

Many developers are jumping directly into AI agent frameworks like:

LangChain
CrewAI
LangGraph

But without understanding the foundations first, things quickly become confusing.

Concepts like:

LLMs
Tokens
Context windows
Embeddings
RAG
APIs

are the real building blocks behind modern AI systems.

So in this tutorial, I simplified the core AI concepts every beginner should understand before building AI agents.

1. What Is an LLM?

LLM stands for Large Language Model.

Models like ChatGPT, Claude, and Gemini are all LLMs trained on massive amounts of text.

They learn language patterns and predict likely next words.

Example:

Input:
“The sky is…”

Prediction:
“blue”

Modern AI agents use LLMs as their reasoning engine.

2. Tokens

AI models do not process text exactly like humans.

Instead, text is split into smaller units called tokens.

Example:

“AI agents are powerful”

Could become:

AI
agents
are
powerful

Every model has token limits, which affect:

memory,
conversations,
and document handling.

3. Context Windows

A context window is the amount of information an AI model can process at one time.

Think of it like short-term memory.

If conversations become too long, older information may disappear from context.

This is why memory systems are important in AI agents.

4. Embeddings

Embeddings convert text into numerical representations.

The key idea:
similar meanings become mathematically close together.

Example:

“I love dogs”
“Dogs are amazing animals”

Different words…
similar meaning.

Embeddings power:

semantic search,
RAG,
recommendations,
and memory systems.

5. What Is RAG?

RAG stands for Retrieval-Augmented Generation.

Instead of relying only on training data, the AI can retrieve external information before answering.

Example:

search PDFs,
company documents,
databases,
or websites.

This is how many modern AI assistants work.

6. APIs

APIs allow systems to communicate.

AI agents constantly use APIs for:

AI models,
web search,
weather systems,
databases,
and automation tools.

Understanding APIs is essential for AI engineering.

Why These Concepts Matter

Modern AI agents combine all these systems together:

prompts,
LLMs,
APIs,
embeddings,
memory,
tools,
and retrieval systems.

Understanding the fundamentals makes advanced frameworks much easier to learn.

I also created:

a full beginner video tutorial
and an open-source repository for this course.

📺 Video:
https://youtu.be/y8DOp4SAT5g?si=qZm7QpA5qEA_kfGp

💻 GitHub:
https://github.com/yisakberhanu/ai-agents-course

Would love feedback from other developers building AI systems.

DEV Community: Yisak Bule

AI Basics You MUST Understand Before Building AI Agent

1. What Is an LLM?

2. Tokens

3. Context Windows

4. Embeddings

5. What Is RAG?

6. APIs

Why These Concepts Matter