De facto is a phrase from the Latin language that means "in fact" or "in practice". It is often used in contrast to de jure (which means "by law") when talking about law, governance, or technique. When talking about law, "de jure" is used to describe what the law says, and "de facto" is used to describe what actually happens.
De facto is sometimes also used when there is no appropriate law or standard, but a common practice, that may not necessarily be widely accepted, exists. For example, the de jure name of Bill Clinton is William Jefferson Clinton. This is his name according to official records. His de facto name is Bill Clinton because this is what he is usually called.