Microwave ovens are pretty futuristic by most standards; they're relatively small, heat things more quickly than conventional ovens, and do so without any easily visible mechanism.
Regular ovens apparently heat food by heating the air around the food. Microwave ovens, on the other hand, use waves at a specific frequency to heat up water molecules in food directly. Metal materials cause problems in microwaves because they reflect these waves.
Bread baked in conventional ovens gets a crust because the heat is coming from outside the bread, from the air. This doesn't happen in microwaves, so the crispy crust of, say, a Hot Pocket, is produced by the cardboard sleeve thing that the Hot Pocket is supposed to be put in. A material on the inside of the sleeve absorbs microwaves and heats up, producing the 'outside heat' that causes crustiness. I had always thought that the sleeve was just meant to hold the Hot Pocket after taking it out of the microwave.
I had a bag of microwaveable pizza rolls that listed these microwave instructions: 6 rolls on a plate for 1 minute. I wanted to prepare 12 rolls at once: how long would that take? 2 minutes seems logical, but the instructions for Hot Pockets say that 1 pocket takes 2 minutes and 2 pockets take 3 minutes. I ended up microwaving the 12 rolls for 1:30 minutes, but now that I know about the whole sleeve business, I might have to reevaluate.
I still don't really know what's going on with microwaves; why does pasta sauce always splatter on the microwave walls when heating? Why can't styrofoam containers be used? Why is rotating important? If cooking over a fire is equated to talking, microwave cooking is like speaking over the radio.