 So, you don't understand all triangles, not a problem. It's really the exact same as all quads, except for triangles. Any action you set is only gonna affect faces with three sides. So with masking, creasing, beveling, Q-Mesh, you name it. Anytime you wanna target triangles, this is what you use. Hope that helps, and as always, hope you have a fantastic day, and I'll see you around.