For example, you want to bake chiffon cake, usually preheat to 180 degrees, then you have to preheat the oven temperature to 180 degrees, the average oven almost wait 2, 3 minutes can be, see the temperature inside the oven has risen, then put the good cake ingredients into the baking.

Preheating means heating the oven for a while before baking the food, and putting the food into the oven at a predetermined temperature, not waiting for it to cool down again.

Expanded:

< p>The placement of the oven's grill is another big point. Before starting the oven, adjust the position of the grill according to the instructions in the recipe. The position of the racks matters a great deal; for example, if you divide the oven into upper, middle, and lower racks, bread baked on the upper rack of the oven will brown and possibly even burn when the temperature rises, as well as bake faster than bread baked on the middle rack.

Some pastry recipes call for pies to be baked on a baking sheet (which doesn't necessarily have to be nonstick) on the lower oven rack. In a gas oven, this places the pie pan closest to the heat source. In an electric oven, place the baking sheet on the middle rack. You definitely don't want to bake foods too close to the heat source, which could scorch them. The baking sheet has a flat, solid surface, and baking the pie dough on a searing hot baking sheet helps the pie to form an even, crispy crust and to hold on to the drippings.

When making regular cookies, some people bake two pans at a time and swap the position of the pans during the baking process. This doesn't work for reduced-fat cookies because when making reduced-fat cookies, there should be increased flow of hot air to evenly bake the cookies, and the second baking sheet blocks the air flow. Bake only one tray of cookies at a time and place it in the center of the oven. If you only have one baking sheet, line it with parchment paper and remove the parchment after baking one tray without cleaning the sheet so that you can quickly bake the next tray. As the baking sheet should be cooled before use, but do not cool the cookie sheet by running cold water over it, as this may cause the sheet to warp.

References:

Baidu Wikipedia-Preheating the Oven