A hotplate is a flat metal (or glass-ceramic) surface that heats up so you can cook in a pan on top of it. On a cooker, it is one of the rings or zones you set a pot on. It can also be a small separate electric plate you put on a table, useful in a tiny kitchen or a lab. The plate is the flat surface, not a dish of food. British speakers often say this; some people say burner, hob, or ring instead, depending on the country and the kind of cooker. It is a practical, everyday word, not slang and not fancy. Though actually, a hotplate stays hot after you switch it off, which is why people warn children not to touch it.