A dot matrix is a 2D matrix of dots that can represent images, symbols, or characters. They are used for electronic displays, such as computer monitors and LED screens, as well as printed output.
In a dot matrix display, the images are estimated using a discrete set of dots instead of lines and shapes. Therefore, the more dots that are used, the more clear and accurate the image representation will be. For example, a 16x16 dot matrix can represent the letter "S" more accurately than a 8x8 matrix. If enough dots are used, the image will appear as a contiguous display rather than a group of dots. This is because the human eye blends the dots together to create a coherent image. For example, newspaper print is made up of dot matrixes, but it is hard to notice unless you look very closely at the paper.
Bitmap images on a computer screen are also dot matrixes, since they are made up of a rectangular grid of pixels. If you look closely enough at your monitor, you may even be able to see the dots that make up the image. But be nice to your eyes and don't stare too long!
While "dot matrix" has a broad definition, it can also be used to describe a specific type of printer. Dot matrix printers, or "impact printers," were introduced in the 1970s. These printers typically use the kind of paper with small holes on each side that are used to feed the paper through the printer. They are called dot matrix printers because they use a matrix of dots to print each character. While they do not have a very high resolution, dot matrix printers are an effective way of printing basic text documents. Therefore, while most businesses now use inkjet or laser printers, some organizations still find dot matrix printers to be an efficient printing solution.