A format, language, or protocol that has become a standard not because it has been approved by a standards organization but because it is widely used and recognized by the industry as being standard. Some examples of de facto standards include: Hayes command set for controlling modems; Kermit Communications Protocol; Xmodem Communications Protocol; Hewlett-Packard Printer Control Language (PCL) for laser printers; PostScript page description language for laser printers
A widespread consensus on a particular product or protocol that has not been ratified by any official standards body, such as the International Organization for Standardization (ISO), but which nevertheless has a large market share. The ISO is a voluntary, nontreaty organization founded in 1946 that is responsible for creating international standards in many areas, including computers and communications.
A standard that comes into being not through an agreement by manufacturers, but due to its widespread use. De facto standards are usually established by companies that are first into a new field, or by large firms that have tremendous influence over the computer industry.