When you visit a web page, that page and all of its associated files (scripts, images, etc.) are stored in a special folder known as the browser's cache.

This makes visiting the same page again at a later time faster because the browser can load these items from the cache instead of from the web.

But over time, the cache gets packed with thousands of files, many of which may become corrupted. This leads to poor or unexpected browser performance and maybe even system crashes.

In order to prevent these problems, you need to manually clear out your browser's cache on a regular basis, say once a week.

To clear the cache in Internet Explorer:

Click Tools
Click Internet Options 
Click Delete Files 
Check the Delete all offline content box  
Click Ok 
To clear the cache in Netscape:

Click Edit
Click Preferences 
Double click Advanced 
Click Cache 
Click Clear Memory Cache 
Click Clear Disk Cache 
Click Ok