Users can add moisture to push the humidity up to 100 percent. That's a good thing, especially if you eat a lot of re-heated microwave food. It's more of a regeneration than a reheating. Microwaves very quickly put the energy into the food, but when we steam the food back to life, it maintains its texture, flavor, and color. It also retains the nutrient value that microwaves have a tendency to destroy with the very high temperatures.
Total humidity is great for steaming vegetables.
High humidity keeps meats and breads from drying out, while the high temperatures brown the outside. To make sure that nothing burns, the oven has a heat-sensing probe that shuts it off when the food reaches a targeted core temperature. Some foods cook better at lower humidity. The Gaggenau is adjustable and has a spritzer feature that adds a little shot of moisture for baking. It's a quick burst of humidity adds volume to the food at the beginning of the cooking process.