As you have seen, most things in TD can be/are ignorant of time, frame number, and looping. Sometimes, we need to sequence things, coordinate more complex animations, and so on. You already know the timeline at the bottom of TD's interface. Refer to the following screenshot:
Nearly all the buttons should be pretty self explanatory. We have the usual transport control, the possibility to step ahead or back one frame using the big + and – buttons, and above this are handles to loop only certain regions of the timeline. By moving these handles, we adjust the RStart and REnd (range start and range end) values at the left of the timeline. Here, we can also change how many FPSes we like (it's highly recommended to do this at the beginning of a project and not later) and how long our timeline should be. Two things might be a bit mysterious though—the big I button and the time path at the very bottom. Both of these have to do with the fact that the timeline is actually controlling...