Single or double cavity ovens are available to build into or under kitchen units. The choice is between built-in to a cabinet at a higher level or built-under which means underneath the work surface.
After this the main decision is whether to have a single or double oven. Some double built in ovens have only one real oven, the second being a cavity with a grill. Here is some more information on features of built in ovens:
Conventional ovens
Conventional ovens can be gas or electric. In a conventional gas oven, the heat comes from the gas burner at the rear bottom of the oven. In a conventional electric oven, the heat comes from elements under the base and at the top of the oven. In a conventional oven, heat rises to give a hotter temperature towards the top of the oven, and a slightly cooler temperature towards the bottom …