Why are there two drain fittings under a dishwasher?

Dishwashers typically only have one drain fitting. However, some models may have a second drain fitting for a garbage disposal. The garbage disposal is connected to the dishwasher's drain line and helps to break down food scraps before they enter the dishwasher. This can help to prevent the dishwasher from becoming clogged and can also extend the life of the garbage disposal.