Skill-based matchmaking — or SBMM — is a system that works to gauge an individual players skill and match them with other players at the same skill level. Ranked game modes essentially double as a form of SBMM. You will always face off against opponents at your skill level.

Why is skill-based matchmaking good?

This is where SBMM is beneficial as it separates the professional and hardcore gamers from ones that just do it for fun and dont have the time to get to a high level of skill. Thus, the good players play amongst each other while the worse ones play with people of a similar level.