Finally, if you want to prevent sites from knowing you visited them at all, you can use a proxy like Tor. With the additional account information, they are associated directly with you.
At other search engines, when you do a search and then click on a link, your search terms are sent to that site you clicked on (in the HTTP referrer header).
We call this sharing of personal information "search leakage." For example, when you search for something private, you are sharing that private search not only with your search engine, but also with all the sites that you clicked on (for that search).
In addition, when you visit any site, your computer automatically sends information about it to that site (including your User agent and IP address).
This information can often be used to identify you directly.
So when you do that private search, not only can those other sites know your search terms, but they can also know that you searched it.
It is this combination of available information about you that raises privacy concerns. Instead, when you click on a link on our site, we route (redirect) that request in such a way so that it does not send your search terms to other sites.The other sites will still know that you visited them, but they will not know what search you entered beforehand.At some other search engines (including us), you can also use an encrypted version (HTTPS), which as a byproduct doesn't usually send your search terms to sites.However, it is slower to connect to these versions and if you click on a site that also uses HTTPS then your search is sent.Nevertheless, the encrypted version does protect your search from being leaked onto the computers it travels on between you and us.At Duck Duck Go, our encrypted version goes even further and automatically changes links from a number of major Web sites to point to the encrypted versions of those sites.