Define Composer and Composer Installation

Composer:
Composer could be a tool for dependency management in PHP. It permits you to declare the libraries your project depends on and it'll manage (install/update) them for you.

Dependency Managers:
Package Manager is used for SYSTEM and Dependency Manager for PROJECT, 

Composer isn't a package manager within the same sense as Yum or Apt are. Yes, it deals with "packages" or libraries, however it manages them on a per-project basis, putting in them in a very directory (e.g. vendor) within your project. By default it doesn't install something globally. Thus, it's a dependency manager. It will but support a "global" project for convenience via the worldwide command.

This idea isn't new and composer is powerfully impressed by node's npm and ruby's bundler.

Suppose:

You have a project that depends on variety of libraries.Some of those libraries rely upon different libraries.

Composer:Enables you to declare the libraries you rely upon.Finds out that versions of that packages will and want to be put in, and installs them (meaning it downloads them into your project)

Example of Dependency Managers:

• Composer (used with php projects)
• Gradle (used with Java projects including android apps. and also is a build tool)
• Node Package Manager (NPM: used with Nodejs projects)
• Yarn
• Maven (used with Java projects including android apps. and also is a build tool)
• and so on.

System Requirements

Composer requires PHP 5.3.2+ to run. A few sensitive php settings and compile flags are also required, but when using the installer you will be warned about any incompatibilities.

Installation - Windows

This is the easiest way to get Composer set up on your machine.

Download and run Composer-Setup.exe. It will install the latest Composer version and set up your PATH so that you can just call composer from any directory in your command line.

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