hey guys is there a website called Google? Just want to know so I can use it to search for stuff that I have questions about.
But since I'm feeling particularly generous today...
http://www.ehow.com/how_2091895_defrag-mac-hard-drive.html
"Defragging a Mac hard drive is a thing of the past because of the way that OS X manages files. After installing system updates or new applications, the computer will optimize itself. There are ways to periodically clean up your computer and defrag a Mac hard drive, but it can take a few hours and may not improve performance significantly."
EDIT: Just thought I'd mention, the link does give you instructions on how to defrag a Mac, it's not just a thing that says "You don't need to."