What is Composer and why does Laravel use it?

 Difficulty: Beginner → Intermediate

Composer is PHP's dependency manager.

Laravel itself depends on many PHP packages.

A Laravel project therefore has:

composer.json
composer.lock
vendor/

For example:

{
    "require": {
        "laravel/framework": "..."
    }
}

Composer installs the required dependencies into:

vendor/

The application loads these dependencies through Composer's autoloader.

A common command is:

composer install

For development:

composer update

should be used carefully because it can update dependency versions according to the project's constraints.