Dependency Manager for PHP.
Composer is a tool for dependency management in PHP. It allows you to declare the dependent libraries your project needs and it will install them in your project for you.
Composer is not a package manager. Yes, it deals with "packages" or libraries, but it manages them on a per-project basis, installing them in a directory (e.g.
vendor) inside your project. By default it will never install anything globally. Thus, it is a dependency manager.
The problem that Composer solves is this:
a) You have a project that depends on a number of libraries.
b) Some of those libraries depend on other libraries .
c) You declare the things you depend on
d) Composer finds out which versions of which packages need to be installed, and installs them (meaning it downloads them into your project).