"Do you like looking at the profiles of people you don’t know that well on Facebook? Of course you do... One wrinkle: there’s now a list of everything you search for on FB.
In addition to your other activity, you’ll be able to see the searches you’re making on Facebook. Just as you can choose to delete any of your posts, you can use the same inline control on Activity Log to remove any of your searches at any time. It’s important to remember that no one else can see your Activity Log, including your search activity."