The Three Broomsticks is one of the local pubs in Hogsmeade. It is known for its delicious butterbeer and its attractive owner Madam Rosmerta, who lives above the pub.
Wizards, much like anyone else, like to have a place where they can unwind and relax, and for the residents of Hogsmeade and the students and teachers at Hogwarts, that place is the Three Broomsticks. This is where wizards go to get Butterbeer, mead, gillywater, red currant rum, Firewhisky and cherry syrup soda.
As is usual among pubs, there are those that cater to the more regular class of clients and those that cater to the fringes of society; the Three Broomsticks serves the regular wizards, leaving the more shady customers to the Hog's Head Inn.
Source: Wikipedia