well, sort of...eventually the space you 'clear' gets overwritten by other stuff....but traces DO remain for awhile...because...all you do when to say 'clear' or 'delete' is to tell your computer that you no longer want that area protected, and it is free to use it. Since new stuff is not the same size size & configuration, it may take awhile.

There ARE programs which can be told specifically to overwrite an area with random stuff..etc...in various degrees of 'wipe'...just like a cursory erasing of a blackboard versus washing it with water. (Sensitive materials in Govt. are sometimes treated like that. Lots of people have things they want to be SURE no one can find.)......I do think that if you 'defragment' your drive, it goes a long way towards writing over things.

Having said all that, it is not a simple task to find un-wiped data!. For most daily purposes a simple delete or cache clearing (dumping) will do...if you are seriously concerned about traces, you would need a program such as...ummm..BCWipe, I think it is. A nice program called PowerDesk, which does LOTS of other things also has a 'wipe' facility built in.