Conventional ovens, which are what most of us probably have in our kitchens, cook food by surrounding it with hot air. Convection ovens, on the other hand, are built with a fan in the back that blows and rotates the hot air throughout the oven. This is why convection ovens generally cook food more evenly than conventional ovens, because the air is not circulating throughout a conventional oven, so some spots can end up hotter than others. Convection ovens also tend to cook food faster than conventional ovens, so they can be a good investment if you want your food to bake more quickly.
Follow the specific instructions given by your oven manufacturer, keeping these general guidelines in mind: