A flash suppressor is intended to dissipate muzzle flash so as not to hamper the firer's vision in low light conditions.

Sometimes, a muzzle brake is mistaken for a flash suppressor. A muzzle brake vents gases from the barrel in a direction intended to counter the recoil of the weapon, thus making it more controllable. However, a flash suppressor does not function as a muzzle brake, nor does a muzzle brake function as a flash suppressor.

Well, a suppressor... suppresses. A flash suppressor reduced muzzle flash. A sound suppressor reduced noise emissions (although nothing like how they're portrayed in the movies).

Suppressors (or moderators) may be attacked a number of ways, depending on the design of the suppressor. Some use the same threads which the flash suppressor uses, and require you to remove the flash suppressor first. However, you must also replace the standard crush washer with a peel washer when doing this. Some are designed to work in conjunction with a flash suppressor designed to facilitate the attachment of a sound suppressor.. Advanced Armaments designs come to mind here, with their suppressor-capable versions of the Blackout flash suppressor.

Sound/flash suppressor.

Yes- IF the flash suppressor is permanently attached by welding or hard (silver) solder, and is not readily removable.