Microwave ovens streamline the process of food preparation, simplifying it and speeding it up in a compact unit. Depending on the type of food preparation for which you plan to use the microwave, you'll either find a solo unit sufficient or require a convection unit.
Conventional solo microwave ovens operate by emitting microwaves that pass through glass and plastic to heat up food. Convection microwaves combine that technology with radiant heating elements that circulate heated air through the food, cooking it more thoroughly.
Like solo microwaves, convection microwave cook, heat and defrost food, but unlike conventional microwaves, they also bake, brown, crisp, grill and roast foods. A solo microwave is suitable if you're mostly only using it for defrosting, heating and reheating foods and supplementing cooking, while a convection microwave is better if you're using it more frequently for initial cooking and meal preparation.
In solo microwave ovens, you can only use glass, plastic or other microwave-safe, non-metallic cookware. Under all but the microwave setting in convection ovens, you can use metallic cookware, too. Because convection ovens provide a variety of cooking modes, they tend to cost more than solo microwaves.