How Do I Defrag On A Mac?

Most new switchers to Mac that I know ask me this question, “How do I defrag on a Mac?”.
Defrag on a Mac is known as optimization. Files on your hard drive can become fragmented over time. Due to the way OS X is built, there’s little need to optimize your HD. As such it hasn’t been really a practice for Mac users to do this. However if you’re really OC about these things, you can use apps such as Onyx to help you with your maintenance.
Here’s a good read from Apple’s support site regarding optimization.