MAMP

MAMP stands for Macintosh, Apache, MySQL and PHP. It allows you to install a full-fledged local server environment quick and easily on your Mac OS X - as Mac-typically simply mount the disk image and drag the MAMP folder in your Applications folder. So whether PowerBook, MacBook or iMac, now you have your development environment for Web projects wherever you go.

If MAMP is no longer needed, it is sufficient simply to delete the MAMP folder - MAMP does not change the installed Mac OS X.