Shapeshifters are a subspecies of humans (normally), but have the power to shapeshift into anything, this includes objects, other creatures, etc.
Shapeshifters look exactly like humans, but they can shapeshift into whatever they want. Other than that, they normally act and are basically humans.
There are some cases of non-human-like shapeshifters, but this is rare, since shapeshifters have parents that are also shapeshifters. It can happen, though.
All Known Shapeshifters