some basic questions

[Eli]

I have gone through the beginners guide and forum and still do not understand the following:

When cleaning windows and applications(other than temp files)what sort of files are this? for example office,antivirus and other applications and of course windows? Will I potentially disable some functions if I delete these files?I'm on default settings. Thanks in advance for your reply.

[JDPower]

It basically deletes stuff like application logs, recent document lists, temp files etc. You may want to leave Office unticked if you use it often though as IIRC it can delete some office settings. And don't tick anything in the advanced section if you don't know what they do.