Oh, sorry, Tag Question is part of English grammar. Please refer to Jura's.

A tag question is one that invites the listener to agree, by adding a “tag” word or expression to a statement. For example “You love me, don’t you?” or "The car is wrecked, isn't it?"

you mean the bookmark function? it play the part of my favourite function which can save any questions or title that of you think practical and interesting. you can also save other places, such as google, myspace, yahoo, the place where you might think it is very convenient