Ovens are used for cooking food.  I want to define them, since they are often wrongly named.

PIZZA OVEN

An oven in which the food cooks in ambient air.  The cool, dry air passes over the food, then enters the wood fire , burns and the flame curls over the roof to be extracted just inside the top of the mouth.  The base transfers heat stored in the floor by conduction and radiant heat comes from above from the flame.  The moment you close the door you exclude the ambient air and the oven no longer functions as a pizza oven.  It is possible to make a gas fired pizza oven, but I can’t think who would want one.  I have a design for an electric pizza oven, but I have never seen one.  A conventional closed electric oven is not a pizza oven, even if it is used for cooking pizzas.  Pizzas cooked in static hot moist air will never taste right or be worth eating. 

DUTCH OVEN

A heavy clay oven.  Generally shaped like a horizontal half cylinder with a chimney at the back.   A fire is made inside and allowed to get very hot for at least an hour.  The fire is then taken out and bread is placed inside.   The oven is then sealed and the bread bakes.  Construction tip; make a good chimney.  We have suitable designs and materials. 

MICROWAVE OVEN

Food is directly heated throughout its volume by electromagnetic waves tuned to the vibration frequency of water.  Heat can escape from the surface of the food, so the middle ends up hotter and the crust does not brown.   A cockroach can walk across your food unharmed because his high ratio of surface to volume allows him to lose heat faster than the microwaves can heat him.

PRESSURE COOKER

Cooks in water/steam, no water or anything is lost. Temperature is above 100C.  Normally heat is added very slowly, and cooking continues for many hours with no loss of moisture.

TANDOORI OVEN

An Indian oven consisting of a vertical cylinder of clay with a wood fire in the bottom.  Bread or roti is cooked by slapping it onto the inside of the wall.

UMU

A Tahitian oven providing some of the best cuisine in the world.  Very simple but lots of work.  Dig a pit, build a big fire in it, add rocks to absorb the heat.  Wrap your food in banana leaves, tightly, and place between the stones, covering it with hot stones.  Cover the whole pit with soil or sand and compact it.  Leave for a few hours to cook with no loss of moisture