Whenever you visit a webpage using the Safari web browser, it gets recorded in you browser history so you can more easily go back and find that page again should you want to. Likewise, cookies get stored to persist things like logins and other information. If you don't want a particular page recorded in your history or cookies (we don't judge!) you can always use Private browsing mode. If you forget, however, iOS 7 lets you quickly and easily clear your history and cookies, and start over fresh and clean.
That's it. All the web data stored in Safari is now gone. Just be sure to repeat these steps each time you don't want your web history to be visible to anyone else.