Why do kitchens get how when a cooker is on?

It has come, into sight that when a cooker stays on, then usually a kitchen gets much hotter. The main reason lies behind this is, the cooker generates more heat, while cooking delicious cooking in such appliances. This is why; it would be good, if people turn off the switch of an oven after preparing any cooking in a cooker. For having any more detailed information, you may consult with some experts, who have some adequate knowledge regarding all such aspects.