How does active frames in street fighter relate to spacing and vice versa

like how certain moves whiff if u do it at a certain spacing regardless wether they be crouching or standing but if u do moves a certain spacing it don’t whiff

0:02 / opponent reaches into active space
Vice’s LK Da Cide Slayer reaches into Dhalsim’s extended B+MP, which gives him enough frame advantage to link c.HP. Dhalsim is actually quite amazing when it comes to these kinds of combos because of the sheer variety of attack ranges available to him. Some characters’ entire arsenals are aimed at a specific spot right in front of them.

0:05 / opponent crouches into extended attack
Guile walks just outside of c.MP range and whiffs one against standing King. Generally speaking, all characters in all fighting games become fatter while crouching. King ducks into the last active frame of Guile’s c.MP which allows him to link into F+HP backfist.