What is Composer in php? - Manage the Dependencies

Question: What is Composer?
Composer is an application-level package manager for the PHP.

Question: Why Composer is used?

Composer provides a standard format for managing dependencies of PHP software.
Composer installs the dependencies libraries.
Composer provides autoload capabilities for libraries.

Question: Where composer is used?
When we need manage the dependencies of PHP application, we can use Composer.

Question: How Composer Works?
It works commond line.

Question: Who developed the Composer?

Nils Adermann.
Jordi Boggiano.

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Question: What is current stable version of Composer?
1.2.0 / July 18, 2016.

Question: In Which language, It was writeen?
PHP.

Question: What is offical website of Composer?
http://getcomposer.org/

Question: What are System Requirements for compser?

PHP 5.3.2+
Need git, svn or hg repository depend of composer version.

Question: What is command to download the composer?

php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
php -r "if (hash_file('SHA384', 'composer-setup.php') === '544e09ee996cdf60ece3804abc52599c22b1f40f4323403c44d44fdfdd586475ca9813a858088ffbc1f233e9b180f061') { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('composer-setup.php'); } echo PHP_EOL;"
php composer-setup.php
php -r "unlink('composer-setup.php');"

You need curl OR openssl enable for above command.

Question: How to install the composer?

php composer.phar install

Question: How to update the composer?

php composer.phar update

Question: How to check current version of composer?

php composer.phar -V

Question: Can I used composer standard for my new project?
Yes, you can start.

Question: Is it open-source?
Yes, It is open-source.

Question: Give me sample of composer.json file?

{
    "name": "zendframework/skeleton-application",
    "description": "Skeleton Application for ZF2",
    "license": "BSD-3-Clause",
    "keywords": [
        "framework",
        "zf2"
    ],
    "homepage": "http://framework.zend.com/",
    "require": {
        "php": ">=5.3.3",
        "zendframework/zendframework": "2.3.2"
    }
}