Sims are the simulated people that players control in The Sims series.
The Evolution of Sims
Sims were first mentioned in the first edition of SimCity (1989) but never could be seen. Their first known appearance was in SimAnt (1991), where they were the owners of the yard the ant colony lived upon. Apparently the first "seen" Sims were a black man, his dog, and a boy which is assumed to be the man's son. You can also see a stray or wandering cat outside the yard that the dog frequently scares away.
Further interaction was given to the Sims in SimTown (1994), and was the base of many concepts that later went into The Sims. Among these, a very basic mood meter was introduced, you could choose certain Sims' favorite things, and you could actually pry into all houses.
After that, no game quite got as close to The Sims as the game itself. However, Streets of SimCity (1997) introduced Simlish for the first time in the radio music. The first game with spoken Simlish was SimCopter (1998).