A de facto standard is a custom or convention that is commonly used even though its use is not required. De facto is a Latin phrase (literally "of fact"), here meaning "in practice but not necessarily ordained by law" or "in practice or actuality, but not officially established". A de facto standard contrasts an international standard which is defined by an organization such as International Standards Organization, or a standard required by law (also known as de jure standards). Joint technical committee on information technology (ISO/IEC JTC1) developed a procedure in order for de facto standards to be processed through the formal standardization system to be transformed into international standards from ISO and IEC. In social sciences a voluntary standard that is also a de facto standard is a typical solution to a coordination problem. The choice of a de facto standard tends to be stable in situations in which all parties can realize mutual gains, but only by making mutually consistent decisions. In contrast, an enforced de jure standard is a solution to the prisoner's problem.

Examples

Examples of some well known de facto standards:

File formats

Connectors and interconnect standards

Materials and units of packaging

Miscellaneous

Standardization disputes

There are many examples of de facto consolidation of a standard by market forces and competition, in a two-sided market, after a dispute. Examples: An example of an ongoing dispute is OASIS's OpenDocument format vs Microsoft's Office Open XML format.