PHP Composer and Autoloading

Composer automates PHP dependency management through a composer.json file that lists project requirements and version constraints. Running `composer install` downloads dependencies into a vendor directory and generates composer.lock to ensure reproducible builds across environments.

PSR-4 autoloading automatically loads PHP classes based on namespace and directory structure without manual require statements. Composer maps namespace prefixes to directories in composer.json, allowing the autoloader to locate and instantiate classes on demand.

Define autoload mappings in the composer.json file by specifying namespace prefixes and their corresponding directory paths. After updating composer.json, run `composer dump-autoload` to regenerate the autoloader and enable class resolution.

Composer scripts allow you to define custom commands in composer.json that execute tests, linters, and other workflows. Run these scripts with `composer run [script-name]` to automate quality checks across development, testing, and production environments.

composer.json defines project dependencies with flexible version constraints, while composer.lock locks exact versions of all installed packages. composer.lock ensures every developer and deployment uses identical dependency versions for reproducible builds.

Yes, committing composer.lock to version control ensures that all team members and production deployments install the exact same dependency versions, preventing unexpected behavior from version mismatches.