While you surf the internet, the web browser keeps a cache containing the pages you already visited. This means that it saves all the contents of the pages you visited, including text and images, to a specific folder on your hard-disk, called cache.
Because of this, when you visit a web page again, the browser is able to quickly show you the page because it already has its content in the cache, and doesn't need to get the contents from the web. The cache feature helps you browse the web faster. However, someone may examine your cache and see what web sites and pages you visited, what images you viewed, etc. Another problem is the fact that in time, these pages that are automatically saved will take up a lot of disk space.
The Mozilla Firefox Temporary Files wizard allows you to examine and delete your cache.
Select which temporary internet files you would like to delete. After you press the "Next" button, the wizard will delete the selected files.