Mixers... what do they do exactly?

my question is... really, what does a mixer do (ie. Mackie mixers)? doesn't Pro Tools already have a mixer (in there software)? like i see some people have Pro Tools then have this mixer on the side anyways i hope u know what i'm talking about as u can see from this question... i AM REALLY NEW and still learning thanks

yeah i "kinda" get the picture but i do get what your saying don't worry i'll learn as i go along i guess with the mixing console it's more of a "hands-on/finger tips" kinda thing but either mixing on the console or mixing in Pro Tools will get the job done i guess but i do have another question: as u know the original Mbox does not have a monitor control and i been thinking of purchasing a pair of studio monitors i was thinking of getting the Behringer Eurorack UB502 to control them but i was wondering if i could control them with a mixer instead (for example let's say the Mackie CR1604-VLZ) would that be possible? thanks again for your reply and oh yeah, nice setup by the way, very nice and clean nice curtains too

Hey Phil, love the studio, I see the AMT8 in that rack of yours, what else you got in there, apart from the 002R? filosofem