A stovetop kettle is a roughly pitcher-shaped metal vessel used to heat water on a stovetop or hob. Kettles usually have a handle on top, a spout, and a lid. Sometimes stove-mounted kettles also have a steam whistle that indicates when the water has reached boiling point. In whistling tea kettles, when the steam building up in the container of the kettle tries to escape, it causes vibrations to occur within the chamber. As the speed of the releasing steam increases, the vibrations become louder, causing a whistle. Some whistling kettles have an actual whistle on a cover at the end of the spout.
The most popular stovetop kettles are made with stainless steel. This is due to the lightweight nature of the kettle, in addition to the bright finish and durability. The crack-resistant nature of the kettle also makes it easier to clean. Kettles can also be made from copper, iron, aluminum, polished chrome or ceramic.
A kettle has two principal advantages over a saucepan for heating water: the enclosed nature of a kettle reduces heat losses and leads to quicker boiling, and the exclusive use of the kettle for water means that hot drinks cannot be contaminated by grease spots or food residues left if saucepans are not meticulously washed.