A kettle, sometimes called a tea kettle or teakettle, is a type of pot, specialized for boiling water, with a lid, spout, and handle, or a small kitchen appliance of similar shape that functions in a self-contained manner. Kettles can be heated either by placing on a stove, or by their own internal electric heating element in the appliance versions.
A modern stovetop kettle is a metal vessel, with a flat bottom, used to heat water on a stovetop or hob. They usually have a handle on top, a spout, and a lid. Some also have a steam whistle that indicates when the water has reached boiling point.
In countries with 200-240 V mains electricity, electric kettles are commonly used to boil water without the necessity of a stove top. The heating element is typically fully enclosed, with a power rating of 23 kW. This means that the current draw for an electric kettle is upwards of 10 A, which is a sizeable proportion of the current available for a typical home: the main fuse of most homes varies between 20 and 100 Amps. For this reason electric kettles, while available, are less popular in countries with 110 V mains electricity, where electric sockets are often current limited to providing around 1.5 kW.
In modern designs, once the water has reached boiling point, the kettle automatically deactivates, preventing the water from boiling away and damaging the heating element. A more upright design, the "jug"-style electrical kettle, can be more economical to use, since even one cup of water will keep the element covered.
Electric kettles were introduced as an alternative to stove top kettles in the latter part of the 19th century. In 1893 the Crompton and Co. firm in the United Kingdom started featuring electric kettles in their catalogue. However, these first electric kettles were quite primitive as the heating element couldn't be immersed in the water. Instead, a separate compartment underneath the water storage area in the kettle was used to house the electric heating element. The design was inefficient even relative to the conventional stove-top kettles of the time.
In 1922, the problem was finally solved by Leslie Large, an engineer working at Bulpitt & Sons of Birmingham who designed an element of wire wound around a core and sheathed in a metal tube. As this element could be immersed directly into the water it made the new electric kettle much more efficient than stovetop kettles.
In 1955, the newly founded British company Russell Hobbs brought out its stainless steel K1 model as the first fully automatic kettle. A thermostat, triggered by the rising steam as the water would come to boil, would flex, thereby cutting off the current.
These are relatively new kinds of tea kettle. They are high tech kitchen appliances that are geared towards making tea brewing easy for everyone. They are built with the capability to intelligently make different kinds of tea without much input from the user.
Once set, the automatic kettle brings the water to the specific temperature for preparing a given kind of tea, adds the tea to the water, and steeps the tea for the appropriate amount of time. Often they will make beeping sound to alert the user when the tea is ready, and maintain the temperature of the beverage after preparation.