A browser is what is used to search the internet, such as Internet Explorer, Safari, Chrome and Firefox. Browsers allow you to enter a question or some questions through a search engine, or go directly to a URL. When you enter this information into a browser and hit enter, the browser sends off the request to the internet and returns the requested information if it finds it. At the point it does this, the browser is downloading information to your computer. This is the functionality a Driveby takes advantage of. As it downloads information to your computer, it can also download viruses.
Browsers also store information in Cookies.