Page description language is a type of computer language used primarily for the printing industry. Computers are generally connected to large printing machines, and by using a specialized language for both devices to communicate, efficiency in setting and printing materials is greatly increased. There are a wide variety of description languages, but the most common is Adobe® PostScript®.
Although many page description language varieties are detailed enough to be considered programming languages, a large portion of them are not. These are known as markup languages. Similar to hypertext markup language (HTML), page description markup languages are capable of speaking to a limited number of programs. Just as HTML is used primarily to speak with web browsers, most page description language varieties can be read by a particular machine, program, or computer.
Page description languages are often created using binary or textual commands. In the case of a binary language, graphical and textual formatting are turned into a series of ones and zeros using the description language. This code is sent to the printer and then transferred back into a visual graphic as it is printed. Binary codes are the same ones used by every computer. When a command is typed into a keyboard, for example, a series of ones and zeros representing the key tells the computer what to do.
The main purpose for using a description language is to better communicate various aspects of a printed material from a computer to a printing machine. Text and graphics are laid out on a computer screen, but using only output bitmaps limits the amount of information that can be received by a printer. Using a page description language relays more information, faster.
The benefits of using page description languages include higher quality materials and more efficient printing. Since information is better received by a printer using page description languages, the color, layout, and resolution is often of a better quality than they would be if the same item were printed without them. These languages can also instruct printers on the quantity of materials to be printed.
In many cases, a programmer is needed to create new page description language code. Some of the easier markup languages may be learned by anyone, although they are limited in their use. Many computer drawing programs already have page description language added in, so that as a graphic or format is created, codes are being written simultaneously in the program's back end.
Most larger printers use some kind of page description language, but it is also possible to take advantage of these programs at home. Software which implements full description languages are often pricey, but it may be worth the investment for a self-employed printer or designer. The cost may also be less in the long term than hiring a professional printer.