De facto standard

A de facto standard is a custom or convention that has achieved a dominant position by public acceptance or market forces. De facto is a Latin phrase in fact in the sense of "in practice but not necessarily ordained by law" or "in practice or actuality, but not officially established", as opposed to de jure.
The term de facto standard is used in contrast with obligatory standards ; or to express the dominant voluntary standard, when there is more than one standard available for the same use.
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.


A selection of well-known and illustrative examples of de facto and de jure standards are:
Examples of long-time de facto but never de jure standards :
Other examples:
Various connectors and interconnect standards - despite being formalized and standardized, almost no product is required by law or other legal standard to use them. Examples:
Materials and units of packaging:
There are many examples of de facto consolidation by market forces and competition, in a two-sided market, after a dispute. Examples:
Examples of standards that are "in dispute" for turns de facto: