# The Importance Of Equivalences

Okay, I asked a question earlier today, Congruence Class $[n]_5$ (Equivalence class of n wrt congruence mod 5) when n = $-3$, 2, 3, 6, pertaining to finding equivalence classes. I already know how to solve such problems, now my question is, what is the importance of having/knowing what an equivalence class is? Does it reveal any sort of information about the relation?