Many of you wonder when and how to defragment a Mac's hard drive; the question comes up most often during the first few weeks of a new year. Sometimes the question comes from readers who got their first Mac for Christmas; other times it's from seasoned Mac users who are determined to start the new year off right, with their Macs in tip-top shape.
Courtesy of Apple
The answer to this question is generally no, you don't need to defragment a Mac. There are exceptions though, depending on how you use your Mac.
OS X has its own built-in method to track and defragment the startup drive, all without any user intervention. It does a pretty good job; so good, in fact, that for the vast majority of users, there is no real need to use a third-party defragmenting utility.
But some of you could benefit from defragmenting your Mac, especially if you need optimal performance for specific applications, such as video and audio production, or video or audio capture.
You can find out more about how your Mac's automatic defragmentation system works in this FAQ: