There are also different ways the keys on a keyboard are laid out, usually to deal with different regions and languages of the world. Most computer keyboards have the keys in six rows, but some laptops use only five or even four rows to save space. The most popular layout is called QWERTY, which is based on the first six letters on them. The QWERTY design was made so that the most common letters would not make the moving parts of a mechanical typewriter "jam", or stop working. Now, even though most people do not use typewriters anymore, the design stayed because people were used to it. Other layouts have been developed, for example the Dvorak keyboard, which puts the most common letters in the places that are easiest to reach. 