Plastic wrap...it can be difficult to work with, doesn't always stick to the bowl, can't be reused and isn't cheap.
I have any easy alternative. I stopped at my dollar store and bought a package of eight shower caps for one dollar. I use the caps to cover items that I'm saving in the refrigerator.
Once used the caps can be washed with soapy water, hung to dry and reused.
To use, wrap the cap elastic around the bowl and poof it up around the top so that the cap will not come in direct contact with your food. You want to make sure that none of the plastic-y chemicals leech into your food.
Economical, environmental and convenient!
