Partitioning a hard drive is helpful for both organization and speed. It also allows you to, for example, run Windows and Linux together on the same PC or, using Apple’s BootCamp, run Windows and Mac OS X alongside each other.
Excerpt from Wired.com.
Simply note to myself. I used to partition all my hard drive, most often to separate the system and data. But never in my MacBook. This is a good note to start it all over again, especially when no data will be affected while partitioning my hard drive.