Your browser lets your computer talk with the internet to display web pages. To do its job, your browser must "remember" certain things. For example, instead of wasting time reloading the same images or even entire web pages, over and over again, your browser will save some of this information for faster downloading times. And, depending on your computer settings, it may also remember addresses of web sites you've visited, documents you've downloaded, your search history, commonly used passwords, and data from advertisers.
Sometimes all that history can cause problems. If you're repeatedly experiencing trouble loading a web page, a first troubleshooting step is to clear your browser cache, cookies, and history. This forces your browser to look for fresh information and stop loading old data.