What is Composer?

Composer downloads and manages PHP packages for your project. Code is often written with a version of code or a framework, and may break compatibility with future updates. Managing the installed versions of these packages becomes very important on large projects. Instead of working from a copy of the version you had at the time, you can record which versions were used and re-download them later if needed. This lets you install updates easier. Since Composer is widely used in the PHP world, packages can declare any version requirements of their own dependencies. This allows you to get the right version when you add new packages while avoiding non-compatible updates.