Now it can refer to different closed circles and produce interaction. For example, in the men's basketball World Cup draw ceremony, Kobe Yao Ming represents the basketball circle and YCY represents the entertainment circle, breaking the "dimensional wall" and creating interaction.
Semantic evolution
The original meaning of the word "secondary element" is a two-dimensional plane and a concept of spatial dimension. Any point of the second dimension can be located by two coordinate axes (such as X axis and Y axis), and the area of the second dimension is usually expressed in 1 pixel.
In Japan, early animation and comic works were all composed of two-dimensional images, and these images were flat, so they were called "two-dimensional world" by animation lovers, as opposed to "three-dimensional world", that is, the real world.
The ACGN cultural circle uses the word "secondary element" to mean "overhead", "imagination", "fantasy" and "fiction", and then refers to "overhead world".