The cache in your browser is where the browser has kept a copy of the web pages you have looked at. Then when you ask for the same web page later that day or soon after the browser can display the page or images on it quicker. If it is in cache and a time limitation is not on the page, the browser uses the copy in cache memory. Otherwise a request must be sent to the web site server and the page sent back.
If you think or know the page has been updated and you are looking at an older version simply press the refresh button in IE or the reload button in most other browsers such as Firefox and Safari. The refresh/reload request send the request to the web page server and bypasses cache memory
Sometime pages that you enter stuff in or are changing pages will get problems mixing whether to do cache or request the page. Students using Angel at the Georgia Technical colleges are told to clear the cache when problems appear.
In Internet Explorer go to the Tools menu. Then choose Internet Options.
In IE version 8 and 7 click Delete in Browsing History section on the General tab. Make sure Temporary Internet Files is checked and then press the Delete button. Depending on when you last did this, it may be quick or may tale a couple minutes. Then close out. You can also do this by using Safety menu item and clear Browsing History.
In Firefox choose the Tools menu and then choose Clear Recent History, click Details then I would suggest change the dropdown to say Everything and then only check Cache (you can clear the others if you want, but history and cookies can be helpful). Then click Clear Now.