Unless you are on the Marangu Route, accommodation on Kilimanjaro will be in tents brought up by your porters. Do not be tempted to sleep in any of the caves, which is against park regulations.
On the Marangu Route, camping is forbidden and instead people have to sleep in huts along the route. The sleeping arrangements in these huts are usually dormitory-style, with anything from four to twenty beds per room. You will see people camping on this route, but they are trekkers who took the Rongai Route to ascend and are now descending on Marangu.
Confusingly, away from the Marangu Route many of the campsites on Kilimanjaro are actually called ‘huts’ but don’t be fooled: they are called huts because of the green shacks that you’ll find at these campsites, which are usually inhabited by the park rangers. Trekkers used to be allowed to sleep in these huts too, but no longer.