What does a airsoft supressor do?

Answer 1

I'm not sure which type of supressor you mean. There are external supressors which screw on to the end of the barrell like a real gun and there are internal supressors. External supressors are purely cosmetic and will not change the way your gun fires. Internal supressors will decrease the noise your gun makes as it fires. They are not too common and need to fitted by a profesional airsmith. My best advice is if you want one fitting to go down to your local shop and ask about them. Hope i helped . :)

You can get a mock suppressor that just makes your gun look cool (and it actually decreases the sound a little bit), one that makes the sound louder, or more recently they started making mock suppressors that when used with certain bb's caused them to light up making a "tracer" effect.

Answer 2

Multiple things. On gas guns it can supress the sound. It can also be used to hide a longer inner barrel for more accuracy. Finally, its mostly for looks.