When we say that the universe is expanding, the space between everything is not. The space between atoms, the space between my house and school, and the space between Earth and Sun remains the same, due to the four fundamental forces of nature.
However, when does the gravitational force becomes comparatively small, to see the expansion in space?
Is it between the stars - interstellar?
Is it between the galaxies - intergalactic?
Is it between the superclusters - intersupercluster?
Or something greater that I'm not aware of?