My daughter spends a lot of time online after school and after she's completed her homework. You have several options to help you gauge where your child spends time online. Keep in mind, however, that the best solution is to spend online time together. Ask your daughter to show you what sites she likes - have her tell you what appeals to her and why. You may choose to install monitoring software.
Web browsers cache, or remember, sites visited.
It's easy to erase the history - give it a try yourself. Finally, always encourage your daughter to discuss what she encounters on the Web. Remind her that respect and honesty are just as important online as they are offline. Sometimes I get caught on one page. Both Internet Explorer and Netscape Navigator have Back buttons.