Explain how Composer manages project dependencies and ensures consistency across environments. Specifically, describe the roles of `composer.json` and `composer.lock` files, how `composer install` and `composer update` commands are used, and the best practices for committing these files to version control.
Navigate to the 'Basic usage' documentation page on getcomposer.org. Read the sections detailing the purpose and usage of `composer.json`. Read the sections detailing the purpose and usage of `composer.lock`, particularly its role in reproducible builds. Read the sections explaining the `composer install` command and its interaction with `composer.lock`. Read the sections explaining the `composer update` command and its interaction with `composer.json` and `composer.lock`. Identify the best practices for committing `composer.json` and `composer.lock` to version control. Synthesize all gathered information into a comprehensive explanation.
The explanation clearly states that `composer.json` defines project dependencies with version constraints. The explanation clearly states that `composer.lock` records exact dependency versions for reproducible builds across environments. The explanation details that `composer install` uses `composer.lock` (if present) for exact versions, or `composer.json` if `composer.lock` is absent. The explanation details that `composer update` resolves the latest compatible versions from `composer.json` and updates `composer.lock`. The explanation states that both `composer.json` and `composer.lock` should be committed to version control to ensure consistent dependency versions across environments and team members.