Broadway usually refers to Broadway theater, which comprises numerous theater venues in the Theater District and the street of Broadway.
New York City's Theater District is an area and neighborhood in Midtown Manhattan where most Broadway theaters are located, as well as many other theaters, movie theaters, restaurants, hotels, and other places of entertainment. West 40th Street bounds it on the south, West 54th Street on the north, Sixth Avenue on the east and Eighth Avenue on the west, and includes Times Square.
Most Broadway shows are musicals. Art historians claim that Broadway musicals became enormously influential forms of American popular culture and "contributed to making New York City the cultural capital of the world".
For the most popular shows, it's better to purchase tickets well in advance.