A chair is a piece of furniture. It is used for sitting on and it can also be used for standing on, if you can't reach something. They usually have four legs to support the weight. Some types of chairs, such as the bar-stool, have only one leg in the center. Those chairs are usually able to spin. Sometimes chairs have armrests. These chairs may be called armchairs. There are many types of chairs such as Windsor chairs and rocking chairs. There is another type of chair called a sofa or settee.