Cleaning the cache

I'm not sure if this is the correct place to post this question but 1) what is the cache? 2)should I clean it? and 3)How do I clean it? I use to use cocktail but my free trial has expired. Is there another free service like this? If this is posted in the wrong location please point me in the right direction

Thanks

This has more to do with the OS X operating system so I will move the thread for you.

I use MainMenu (correct spelling) from Santa Software. It does what I need. There is also OnyX from Titanium Software. I clean out the cache whenever the system is acting weird.

MainMenu can also do the daily, weekly and monthly tasks and other stuff as well.

MainMenu is the grate software many thanks for help! Onyx is much more powerful than i thought !
thanks for the Help ))

There's also this app CacheoutX which does just what the name says... But I guess you are already happy with Onyx and MainMenu...