Dot matrix printers have a horizontally moving head with a vertical line of pins mounted inside. An inked ribbon is located between the head and the paper and as the head moves the pins strike the ribbon to form each character as a series of dots. The best quality printers have heads with 24 pins and low quality ones have 9 pins (although by making two passes and shifting the head half a pin pitch between them they can effectively act as as a 18 pin head). As these printers can produce small dots anywhere on the paper most support graphics and have software fonts. Dot matrix printers are quite noisy but can be cheap. They are mostly for low to medium quality, low volume personal use. They are obsolete now.