Search engines are tracking what you do online. Your computer has an IP address, similar to a post-office mailing address, and by monitoring it search engines know what websites you are visiting. This helps them send targeted advertisements to you but also creates a record of your surfing history. If you have a disease and are searching for a cure there is a trail. And many times what you’re searching for can be misinterpreted. If you search for “terrorist groups” does that mean you are looking to join one? Some are pushing for an option to opt-out of tracking, similar to the ‘Do Not Call’ list. Until then you may consider using a proxy server that allows you to connect to another computer to do the surfing for you.