Plumbob

A PlumbBob is used in most titles of the Sims series to identify the character selected. It is also used to show the mood of your Sim. In The Sims 2, the plumbob is white if the Sim has a very high mood, bright green if the sim's mood is high, bright red if it is low, or if mood is somewhere in between then it will be a shade of green-yellow reflecting the approximate level.

Also in The Sims 2, Sims who belong to the same active group as the selected sim will have a smaller plumbob over their head. This plumbob is blue, irrespective of mood.