Refers to a standard that is widely adopted in practice, even if not formally endorsed. Often used in technology and business contexts. Compare with デファクトスタンダード, which is the loanword equivalent.
See also: デファクトスタンダード
This file format has become the de facto standard in the industry.
事実上標準として広く使われているプロトコルだ。
It is a protocol widely used as a de facto standard.
Loanword from English 'de facto standard'. 事実上標準 is the native Japanese equivalent, often used in more formal or explanatory writing.
Compound of 事実上 (de facto, in practice) and 標準 (standard).