AI Nexus

An Interactive Tutorial

AI Nexus

by Kartikeya Kumaria

A hands-on introduction to large language models, retrieval and AI agents: learn how modern AI actually works by using it yourself, no experience required.

Table of Contents

Introduction: Why This Guide Exists
  1. Part I — Foundations
    Chapter 1Tokenization and the Cost of a Request

    The exact token count Claude actually bills for, and what that costs to call.

  2. Chapter 2Large Language Models

    How a model turns a prompt into a reply, one token at a time.

  3. Chapter 3Retrieval-Augmented Generation

    Teaching an AI to look things up before it answers.

  4. Part II — Applied Techniques
    Chapter 4AI Agents and Tool Use

    Watching an AI decide, act and use outside tools on its own.

  5. Chapter 5Automatic Text Summarization

    Ranking a document's own sentences to condense it, without inventing a word.

  6. Chapter 6Semantic Caching

    Skipping a model call entirely when a new question means the same thing as an old one.

  7. Chapter 7Evaluating AI Outputs

    Scoring an answer against a reference instead of just eyeballing it.

  8. Part III — Beyond the Model
    Chapter 8These Concepts in the Real World

    Real companies, real numbers: how this stuff is actually used at scale.

  9. Chapter 9The System Behind This Tutorial

    A behind-the-scenes tour of the system running these chapters.

  10. Chapter 10How This Tutorial Was Built

    The story of how an AI coding assistant and a person built this, together.

Glossary of Key Terms
AI Nexus: An Interactive TutorialPage i
Introduction: Why This Guide Exists