Description:
"Local development refers to the process of building a website or Web application from the comfort of a virtual server, and not needing to be connected to the Internet in order to run PHP and MySQL or even to test a contact form. One of the most annoying parts of development, at least for me, is the constant cycle of edit, save, upload and refresh, which, depending on bandwidth and traffic, can turn a menial task into a nightmare. With application platforms such as WordPress, which require a server back end to work, you would normally be constrained to develop on a live server, with the headaches that go along with that. MAMP and its Windows counterpart, WAMP, are tools that allow you to locally develop applications that require a server on the back end."
Link:
http://wp.smashingmagazine.com/2011/09/28/developing-wordpress-locally-with-mamp/