There are many reasons why you might want to buy a height adjustable desk. A standard desk is about 72cm high and is designed for people of average height and reasonable mobility. An enlightened employer
may want to have office furniture which is adapted to suit workers outside the averages or with reduced mobility. In fact, many people interpret recent legislation regarding health and safety at work and disability discrimination as requiring employers to make height adjustable desks available to those who require them. Some classes of workers often want to use sit-stand desks, ie desks which can be easily transformed for use either sitting or standing. Many graphic designers, architects etc prefer to work in this manner.
There are basically three different types of height adjustable desk: fit-and-forget, mechanical and electrical. I will describe each in turn.