I picked up the clarinet in 5th grade and played in school bands through college. I knew that it was a Bb instrument but was never taught what exactly that mean

I picked up the clarinet in 5th grade and played in school bands through college. I knew that it was a Bb instrument but was never taught what exactly that meant. I assume it was because my instructors never felt that it was important for their players to know. Since we always played off sheet music that was written for the specific instruments, that's probably true. It's nice to finally know.