In the dictionary
roof‧top noun [countable]
the upper surface of a roof
So, according to the definition, anything that is the upper surface of a roof is called a rooftop.
I can not visualize that.
Say, this kind of family houses (the below picture) is very common in Asia. In America or Europe, family houses are not often built like this:
And this is roof brick
Look at the 2 pictures, the house has 3 floors.
The ceiling of the third floor is not made of roof brick (see the picture 2). After the third floor, they don't build a fourth floor, but an open space which has its floor made of cement just like other floors. They also build some barriers around there.
And there they also build a roof that is supported by a post or some posts, which is used as shelter from rain or sunlight.
People can take in fresh air there or barbecue or have parties or do exercise.
My question is that:
Is the open-space 4th floor called a rooftop?
Is the top of the roof of the shelter also called a rooftop?