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Introduction to Composer

» Composer is a dependency manager for PHP that makes it possible to define third-party code packages used by a project that can then be easily installed and updated. It leverages the built-in class autoloading features of PHP, repositories of PHP packages such as » Packagist, and common project layout and coding conventions.

For example, if a PHP application or website needs to work with UUID values, » Ben Ramsey's ramsey/uuid package that implements the widely known and used types of UUIDs that are defined by » RFC 4122 could be used.

Briefly, this is done by creating a composer.json in the project, using Composer to install the latest version of the package, and including Composer's autoload script to make it available to the code. The » Composer "Basic Usage" documentation goes into this in more depth.

Example #1 composer.json that requires a single package 

{
    "require": {
        "ramsey/uuid": "^4.7"
    }
}