Composting food scraps and yard "waste" keeps valuable organic material out of landfills and puts it into your yard or garden. There, this homemade humus enriches your soil without the use of expensive and polluting chemical fertilizers.
As for the worms, they are nature's best little composters.
Find out more in The Care and Keeping of Worms, Shedd Aquarium's How-to Guide for the Novice Vermiculturist (PDF).