Brightness is a very important feature that is taken into account, in combination with the projection distance and the maximum diagonal you want to achieve, for the selection of a projector.

This particular one has a brightness of 2500 Lumens which indicates how much light the projector can deliver on a specific surface size. The general rule suggests that brighter projectors should be preferred in rooms with plenty of light or multiple light sources, while darker ones should be preferred in dark rooms.