Why preheat?!
Answers: why preheat oven?
Especially when baking, it is important to preheat the oven so the batter or dough begins to cook quickly. If the batter or dough warmed with the oven, the butter would melt in the dough much sooner and the consistency of the finished product would change.
Also, slowly warming foods as the oven preheats allows bacteria to grow, which could cause food poisoning
just because.
Because most cooking times in recipes are written for the period at that temperature.
so the oven is ready to bake the food duh!!!
I only preheat when I bake because you have to start the baking process quickly. A lot of other stuff I just put in the oven and let it get a start cooking as the oven heats up.
you preheat because when the oven is first turned on, an electric oven will use both bottom and top heating elements to bring oven to temp. if you just put the food in, like cookies, or cake, the top would burn, bake too rapidly at first, uneven heat, all kinds of problems. Always better to preheat.