Hot Topic in HD?

Hey guys...since I am new to IF and dont know much about it,,,so I just wanted to ask what is the hot topic, normal topic, sticky topic etc. here that I see on this HD forum??? There are different colors on each topic that differentiate it from hot ,normal etc. Just saw that my FF has been marked as Hot topic. hehehe 😆. Glad. But how does it happen and who does it????