Bathtub

A bathtub is an object that appears in most of The Sims games. The primary use is improving a Sim's hygiene, as well as other traits or moods.

Some bathtubs have shower fixtures, but most do not.

The Sims
Bathtubs in The Sims (and expansions) also provide Comfort.

The Sims 2
Bathtubs in The Sims 2 (and expansions) also provide Comfort. All bathtubs allow Sims to take bubble baths, which give more Comfort, but are slightly less efficient at providing Hygiene. Hygiene scores are given as Bath/Bubble bath/Shower (if applicable). Comfort scores are given as Bath/Bubble bath.

If Pets is installed, bathtubs are used to bathe dogs.

The Sims 3
Bathtubs in The Sims 3 (and expansions) also provide stress relief.

The Sims Medieval
In The Sims Medieval, bathtubs provide a positive buff.