Book

• Intro
• Basic Usage
• Libraries
• Cli
• Schema
• Repositories
• Community

Articles

• Aliases Alias branch names to versions
• Custom Installers Modify the way certain types of packages are installed
• Handling Private Packages With Satis Host your own composer repository
• Scripts Script are callbacks that are called before/after installing packages
• Troubleshooting Solving problems
• Vendor Binaries Expose command-line scripts from packages

FAQs

• How Do I Install A Package To A Custom Path For My Framework
• Should I Commit The Dependencies In My Vendor Directory
• Why Are Version Constraints Combining Comparisons And Wildcards A Bad Idea
• Why Can't Composer Load Repositories Recursively

PDF Docs

The whole documentation is also available as a PDF download.

API Docs

If you need to work with composer as a library you may also want to check out the API Docs