|Game:||The Sims, The Sims 2, The Sims 3|
Walls are part of buildings, and can be added or removed in Build Mode. Walls define rooms, and keep the inside in and the outside out - which is particularly important with The Sims 2: Seasons and The Sims 3: Seasons. Some items, such as paintings, toilets, some sinks, fire and burglar alarms need to be placed against walls. Walls can also be built diagonally which will give the house more interesting shapes. In The Sims 2 and The Sims 3, windows and doors can be placed on diagonal walls, which was not possible in The Sims.
The Sims 2 allows either 2000 or 2100 wall segments per lot  before the game will not allow a player to add any more - half-walls are included in this limit, but fences are not. This limit has either been substantially increased or eliminated altogether in The Sims 3, though the upper limit (if any) is unknown.
Walls can be covered by paint, wallpaper, brick, stone, wood panels and siding, etc. to increase the mood of Sims. Walls not covered will give Sims negative moodlets[TS3]
Half Walls are a special kind of wall, introduced in The Sims 2: Nightlife and The Sims 3: Late Night. Half Walls are comparable in height to fences, but are completely solid, and can be painted just like a full wall, but mostly uses the bottom part of the wall paint. Its covered top also have different colours in The Sims 2 and can be recoloured using Create-A-Style in The Sims 3. Fireplaces, doors and windows, and other wall objects cannot be placed on half walls, but fence post lights can be put on the posts of the half-walls. There are different kinds of half-walls that have different tops, designs on the tops[TS2:NL] and colours[TS2:NL].