Bathrooms, by definition, typically contain a combination of sinks, a toilet, a bathtub and perhaps even a shower or a shower-bathtub combo in some cases. These 4 fixtures are the key components of what can make up a bathroom. However, just like how bathrooms come in different sizes, bathrooms also come with different combinations of these fixtures.
Bathrooms often consist of:
a toilet
a sink
a light
a vent
and perhaps some other things...
like a place to hang toilet paper
bathrooms are built often into houses and businesses