A subculture is a group of people with different ideas and ways of doing things than the larger culture they are part of.
Subcultures can be seen as interesting or strange, depending on the person thinking about them.
Examples:
The skateboarders have their own subculture.
In the big city, there are many subcultures.
The subculture has its own music and clothes.
The subculture of cats who like to swim is very strange.
In the future, there might be a subculture of robots who like to dance.
The subculture of people who like to eat only green food is very interesting.