From BR Bullpen

The dugout is a sunken area adjacent to the field where a team's bench is located. Dugouts are standard in professonal parks, but many amateur parks have field-level benches instead. There is normally one dugout located near each foul line between home plate and either first base or third base; it's common but not universal for the home team to occupy the first base dugout.

The dugout is normally roofed and walled on three sides, with only the side facing the field open. The field side of the dugout has steps leading up to the field and often a short chain-link fence to protect the occupants from foul balls. Accomodations are fairly spartan. There is a bench set at a level so that seated players' heads are a short distance above field level, racks for storing equipment like bats and batting helmets, and a water cooler. Modern parks have an exit in the back of the dugout that connects to the team's clubhouse, which is much more luxurious. The dugout is also equipped with a telephone that allows the manager or pitching coach to talk to other places in the stadium, most notably the bullpen.

The dugout, including the dugout steps, is not part of the field of play. A fielder who falls into the dugout while or immediately after making a catch is treated the same way as one who falls into the stands. A player who abandons his attempt to reach first base, or who has failed to touch home while trying to score, may go back and try to touch his base as long as he stays on the field; after reaching the dugout he may not go back.