Learn to think about security clearly.
Free cybersecurity books, lessons and exercises for everyone who wants to protect people and technology. Choose your path and study without an account.
Learn the common language before specializing.
Twenty-three areas. One connected route.
Start at 01 and follow the suggested sequence, or open the area you need. Each one adds a different lens to the same security decisions. Choose a study level inside any area.
Understand the landscape
Start with shared language, information, people and the decisions that govern security.
Design trustworthy systems
Turn principles into architecture, identity, networks, platforms and software.
- 07Security architecture and engineering
- 08Cryptography and trust services
- 09Web3, blockchain and cryptoasset security
- 10Identity and access management
- 11Network and communications security
- 12Systems, endpoints and hardware security
- 13Cloud and container security
- 14Application and software supply chain security
Operate, respond and investigate
Detect what changed, contain incidents, examine evidence and test defenses.
Apply to emerging and critical settings
Carry the same reasoning into AI, post-quantum, industrial and critical systems.
Two ways to find your next lesson.
Choose your route. Both paths show every subject in order and open chapters that have teaching text.
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Learning you can verify.
Each course has one book. Subjects organize modules, weekly chapters group daily lessons, and each lesson has a worked example and an exercise. The reader shows what is published and keeps previous, index and next navigation close to each lesson.
Read the editorial standard →Open text with its course and edition identified.
Read courses, books and exercises without an account.
Public API, Markdown and read-only MCP server.
A library other AIs can consult.
ChatGPT, Claude, DAI and other tools can discover courses and read lessons through MCP or the open API. Every response identifies its public manuscript.