Terminus
What a terminus is
A terminus is the last stop that a particular run of a bus reaches. The place name in the "bound for [name]" shown on the destination sign at the front and side of the bus is precisely that run's terminus. When the bus arrives there, every passenger gets off and that bus's time in passenger service comes to a pause. The stop where the run began, conversely, is called its origin.
What deserves care is that the terminus of the route and the terminus of the run are two different things. Even within one route, "short-turn" runs may be scheduled that finish partway along, either to head into the depot or to match demand. Board with your guard down because the route number is the one you know, and you can find yourself put off the bus short of your destination.
How to tell before you board
Whether an approaching bus goes as far as the stop you want is something you tell from its destination sign. The closer your destination is to the far end of the route, the more attention short-turn runs deserve. Timetables at the stop normally mark short-turn runs with a symbol or a note as well, so one glance before you board settles it. It is also worth remembering that late in the evening there tend to be more runs that finish near the depot.
If the only buses in a given period are short-turn runs, alternatives worth considering include riding to that run's terminus and transferring to a following bus, or taking a different route. On a route you do not know well, asking the crew as you board, "does this bus go as far as [name]?", is the surest method of all, and though it feels like a detour it usually turns out to be the shortest way around.
What happens beyond the terminus
A bus that reaches its terminus does not simply vanish. In most cases it waits and is checked over at a turnaround point or a depot, and then either turns around to become a run in the opposite direction or finishes service and returns to the depot deadheading. That is why you see buses displaying the kaiso, or deadheading, sign near a terminus.
Give yourself a little time to spare when getting off at a terminus, too. Since it is the stop where everybody gets off there is no need to rush, and it is a good moment to check that you have left nothing behind on board. On a day when you plan to ride all the way to the terminus, the ease of knowing you cannot miss your stop even if you doze off is one of the pleasures of traveling by bus.