In Sims 1, 2, and 3, Sims are limited to travel within their neighborhood/world and its subneighborhoods. Sims 1 enabled players to add neighborhoods in-game, so neighborhoods were known as Neighborhood 1, Neighborhood 2, and so on up to the maximum of 99. Sims 2 neighborhoods created by players were created by using external terrain editing programs. Lots were added to new Sims 2 neighborhoods in game. In Sims 3, player created neighborhoods were made by using the Create a World program released by Maxis/EA Games. Lots and rabbitholes were created for neighborhoods in the Create a World program.
In Sims 4, neighborhoods/worlds have fewer lots in them, but Sims are able to travel between them to visit other Sims residences and community lots/venues. As of August 2015, no tool has yet been developed for players to create new neighborhoods/worlds.