in IE, use the Internet Options to remove all temporary files. There is a limit to the size of the directory in which they are kept and will overwrite when it fills up.
Similar removal techniques are available in all the other browsers out there.
You can do the same on a Mac or Linux box too.
when you go onto web and you are looking for something. you look at loads of web pages in the year,are they stored on your hard drive or some wear else,if they are on the hard drive how do you delete the site you have been on.?