Moodlet
Moodlets are mood altering events or situations that a Sim has done or experienced. Depending on what happened, the moodlet will either be a positive one or a negative one. Some moodlets happen for an infinite amount of time while others are timed. Infinite moodlets happen when your sim is on a beutiful lot (such as a beach) or if there are dirty/filthy/vile surroundings when your sim is on a messy lot. Sometimes you may come across a "bug" where you may have a lot where you have a beutifully decorated lot (40+ mood) yet you have vile surroundings (-40 mood) so overall you have no mood effect. (If you have the moodlet manager you can use it to eliminate some of the negative moodlets. (WARNING! if you choose to cure and get a red beam - a negative effect - you will become exhausted.)