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AI Basics - What is LLM (Large Language Model)

[Last Updated: Jan 6, 2026]

Large Language Models are the engines behind modern AI like Gemini and ChatGPT. This tutorial breaks down what they are and how they work.

1. The Definition of an LLM

An LLM is a computer program trained on a massive scale to understand and generate human-like text.

What makes it "Large"?

  • Data: They are trained on trillions of words from books, code, and the internet.
  • Parameters: They have billions of internal connections (like neurons in a brain) that help them recognize patterns.

2. How the Technology Works

Most LLMs use a technology called the Transformer. This architecture allows the AI to understand the relationship between words in a sentence, regardless of how far apart they are.

The Power of Context

LLMs use a process called "Self-Attention." This helps the model decide which words in a sentence are most important to the meaning. For example, in the phrase "The apple fell from the tree because it was ripe," the model uses attention to know that "it" refers to the apple, not the tree.

3. Leading Examples of LLMs

Different companies build their own models. Here are the most common ones you will encounter:

GPT-4 (OpenAI)

Known for strong reasoning and creative writing capabilities.

Gemini (Google)

Designed to be multimodal, meaning it can handle text, images, and video simultaneously.

Llama 3 (Meta)

A powerful open-source model used by developers worldwide.

Claude (Anthropic)

Focuses heavily on safety and being helpful while maintaining a natural conversation style.

DeepSeek

Open-source with strong coding capabilities

For Developers:

You don't need to build the model yourself. Interact an existing LLM model of your choice via:

  • Online Chatbots (ChatGPT, Google Gemini)
  • APIs (OpenAI, Anthropic, etc.)
  • Local models (via Ollama, LM Studio)
  • Cloud platforms (Google AI Studio, Hugging Face)
  • Integrated Development Environment (IDE) Assistants (GitHub Copilot, JetBrains Junie)

4. What can you do with an LLM?

Because they understand language patterns, they are versatile tools for:

  • Writing: Drafting emails, essays, or stories.
  • Coding: Writing or fixing programming scripts.
  • Learning: Explaining complex topics (like physics or history) in simple terms.
  • Analysis: Summarizing long documents into a few key points.

See Also