The Genealogy Data Standard

GEDCOM (ɡɛdkɒm) is the standard for genealogical data. GEDCOM is a file format for exchanging genealogical data between different systems. GEDCOM allows you to export your genealogy data from one application, and then import it into another. GEDCOM is a de facto standard, supported by practically every genealogy application.
As a user, you should make sure the genealogy software you use supports GEDCOM, so you can transfer your data from one application to another.

The GEDCOM specification is the technical documentation for the file format. The GEDCOM Specification tells developers the details of the file format, how to read and write GEDCOM files.
This website is the official home of the GEDCOM specification. It offers a FAQ, a GEDCOM version overview, of course the GEDCOM specification itself. This is complemented with some GEDCOM samples and links to third-party GEDCOM validators.

The latest version of GEDCOM is GEDCOM 5.5.5, released on 2 Oct 2019. It succeeds GEDCOM 5.5.1, released on 2 Oct 1999.