[Satcomer]

Well two things in software maintenance are going on. first there is the Logs that OS X keeps (you can view these logs using /Applications/Utilities/Console). You can read about the history cleaning (rotating is more like it) by the web page Running the Mac OS X maintenance scripts. Plus clearing the cache involves the system startup/shutdown cache & web cache.

To run all the routines needed I use the freeware/donationware Yasu. Other people like the freeware/donationware application Onyx and use it's cleaning routines. Now once the cleaning is done and the program reboots your Mac then upon restart do another manual restart to completely rebuild the shutdown/startup cache.

Lastly doing the "cleaning" IMHO should only be done about every three months. This should keep OS x running fairly fresh (barring any hardware problems).