Through web searches that we make, our browsers keep track of the sites visted. Cookies
from those particular searches are also saved unless one edit's the browser settings.
Sometimes one may want to keep some particular searches private probably to avoid anyone using the computer from knowing or atimes because the search might sound a bit embarrassing. It might be a medical term or anything. Anyway the cookies recieved also makes it easy for those sites to track you. And so, just to begin with and step up your private searches a level higher, use Private Browsing mode
Private browsing mode allows one to browse without saving the cookies from the sites visited. This prevents the particular sites from tracking you on frequent visits.
You might start with this simple step and stop exposing your privacy to the world.