You have a number of ways to go. You can put slick tires on a mountain bike, buy a hybrid which is in between, or go full roadie. Even Road bike have varying layouts.
If you want to do a lot of commuting, you will want wider tires, fenders and racks. Touring bikes are road bikes with drop bars, but wider wheels/tires, clearance for fenders and braze on connections for fenders and racks.
If you don't need to carry a change of clothes and shoes, you can get away without a rack and just use a handlebar bag.