Glossary

Composer

Composer is the dependency manager for PHP. It resolves which packages are needed, downloads them, resolves version conflicts, and generates an autoloader. Nearly every modern PHP project starts with a composer.json.

Key commands

composer require vendor/package — add a package
composer install — install dependencies from composer.lock
composer update — update dependencies and regenerate the lock file
composer dump-autoload — regenerate the autoloader

composer.json vs composer.lock

composer.json — version ranges ("^2.0"). composer.lock — exact versions pinned at install time. The lock file ensures everyone on the team and CI servers use identical versions. Always commit composer.lock.