Community lot
A Community lot is a public lot which serves as the basis for commercial or recreational buildings/facilities in a neighborhood, such as shops, parks, etc. These lots often provide important services for a neighborhood, such as selling clothes, groceries, and magazines; and providing gathering places and entertainment. Townies and playable Sims alike often appear on community lots to browse the goods, socialize or just hang around, so community lots are great places for Sims to make friends. Community lots are great places to meet the hard-to-find service Sims as well. Some (commercial only) objects can only be placed on community lots, and likewise some objects can only be placed on residential lots.
The Sims
Community lots first appeared in The Sims: Hot Date, and each The Sims expansion pack after that introduced a new sub-neighborhood with its own community lots. In order to visit community lots outside of Magic Town, Sims must call a cab, and may have to pay for the ride. (Magic Town's community lots may be visited by using the Hole in the Ground.) When Sims visit a community lot, their residential lot is saved, and will not change until they return home.
All The Sims community lots have an NPC who serves as a janitor. This NPC does general clean-up and repair work on the lot.
Except for Vacation Island lots and family members on Downtown lots, non-controllable Sims on The Sims community lots cannot be interacted with until they are either greeted, or autonomously interact with a controllable Sim.
Babies cannot visit community lots, and Sims will not be able to visit a community lot if that would leave a baby alone in the house. Children can only travel to community lots on Vacation Island, and in Old Town and Magic Town. Children can travel to Magic Town on their own if they use A Hole in the Ground.
Neighborhood children and pets will only appear on Old Town community lots.
The Sims 2
Residential lots also become static when a Sim visits a community lot. Sims do not age while on community lots, but their aspiration level will still decay. Babies and toddlers cannot visit community lots. Children can, if they are traveling with older household members. If a child is taken to a community lot, neighborhood children may appear with one or both of their parents, or a child Townie may appear.
University
Young adult Sims are able to build skills on university community lots. University community lots cannot be visited by Sims in any other age group unless they are invited by a young adult Sim. The semester timer continues to run while a young adult Sim is on a university community lot, but time on the residential lot will still be stopped. However, if a young adult Sim visits a community lot in the base neighborhood or in another sub-neighborhood, the semester timer will pause until he or she returns to the university sub-neighborhood.
Nightlife
Nightlife introduces the ability for Sims to have cars, which they can drive to community lots.
Open for Business
Playable Sims can buy community lots, and establish businesses on them. A lot's owner, and members of their household, can build skills on that lot, though the progress bar will not appear. When the player sends a lot's owner or a member of their household to that lot, the Sims will be able to access their inventories, enter Buy Mode and Build Mode, and even to save.
Pets
If Sims take their pets to a community lot, stray pets may appear on that lot.
Bon Voyage
Bon Voyage introduces the ability for Sims to walk to community lots.
Apartment Life
Apartment Life allows Sims to visit community lots using a helicopter, granted they own a helicopter and helicopter landing pad of course. If the Sim is a witch or warlock, they can use the option "Fly to" to go to community lots. They take out a broom and fly to that lot.
Pets for Console
Unlike in the PC version of Pets, in the console version there is only one community lot in the whole game, that being Town Square. The park is a place where Sims can take their pets to interact with other Sims and pets, where all the events are held, and also where all the shops are located. Pet Points are used in this community lot instead of Simoleons.
The Sims 3
Sims can perform the same actions on community lots as they do residential lots. Babies and toddlers can visit community lots with an adult Sim. Community lots can only be placed on designated areas in the neighborhood. Time is not held static when a Sim visits a community lot. Several community lots are rabbit holes. Sims can own or be a partner of certain rabbit holes. These options are only shown when the household has enough Simoleons to perform the action. Sims can visit community lots by walking, riding a bike, or taking an automobile. There are no loading screens when a Sim visits a community lot.
Lot assignments
There are several classes of community lots, largely determined by lot assignments. Upon release, the game determined these classifications according to the objects on the lot, but a patch altered this. They are now set either in the Create a World tool or from a drop down menu in edit town mode.