Adams apple???

[BoyTeen1997]

What exactly is the purpose of the Adams apple? Also, why do some guys get a VERY noticeable Adams apple and on some guys, it barley shows?

[IAMWILL]

The adam's apple is a piece of cartilage that surrounds the larynx (aka voice box). It becomes more noticeable when one goes through puberty because the larynx expands and pushes the piece of cartilage, the "adams apple", out. (the reason your voice gets deeper. No, its not because your balls "drop", that doesn't happen either).
The reason some people's stick out more than normal is simply the shape or their neck, however in general one who has gone through puberty will have an adams apple that sticks out further.