If you know the meaning of the second type of "data spill" as in the underlined, even if you're not a computer expert, please let me know what it means. I think "the transferred website" can contain the previous page's personal information entered, not the address like www.usingenglish.com.

gu121)"Data spills" means that your personal information is disclosed to some people on the Internet. Many spills happen when you navigate from one website to another. The second site is notified by your browser of the identity of the first site, which might contain confidential information. Then, the data you entered on the first site could be transferred to the second. Data spills can also occur as a result of survey information that gets placed in a website address. When you fill out a form with personal information, you're sometimes taken to a page whose address contains the information you entered. This address could be seen by a third party, who then would have access to your private data.