Understanding the Riot ID
Valorant does not use a single username — it uses a Riot ID, which is a Name plus a short Tagline joined by a #, like Phantom#NA1. The Name is the part opponents and teammates read in the killfeed, so it should be short, clean, and instantly readable at a glance. It can be up to 16 characters, and the Tagline keeps everyone's ID unique so you rarely have to fight for a name.
Competitive players tend to pick tight, aggressive Names — a single strong word or a clan tag plus a word. Generate a batch above, copy your favorite into your Riot Account settings, and choose a Tagline that matches your region or personality.