GEDCOM is a file format for genealogical data. GEDCOM is supported by practically every genealogy application. This allows you to export data from one genealogy application and import it into another.
GEDCOM is originally an acronym for genealogical Data communication.
That name is a misnomer, as GEDCOM neither is nor contains any communication protocol. GEDCOM is just a file format.
The name is kept because it is firmly established.
A GEDCOM file is a structured text file, in which each line is a record or subrecord.
GEDCOM files usually have the file name extension
It is possible to load a GEDCOM file into a text editor to make manual changes, but this is not recommended;
it should not be necessary, and it is easy to make mistakes.
There are utilities to perform common tasks, such as stripping all living persons from a GEDCOM file.
Desktop genealogy application typically have an Export item on the File menu. Web applications typically have a Download menu item. You will generally be presented with a dialog box in which you select what to export.
Desktop genealogy application typically have an Import item on the File menu.
Web applications typically have an Upload menu item.
Some applications allow merging a GEDCOM into an existing database; it is generally best to import a GEDCOM file you received into a new database.
A limitation of GEDCOM is that GEDCOM file do not contain pictures, but only links to pictures.
That is sufficient when you are using multiple genealogy applications on a single computer,
but not when you are transferring your genealogy data to another computer.
When transferring your genealogy data to another computer, you must transfers your pictures, scans and other images separately. We recommend keeping all the multimedia files you use with your genealogy in a single directory. You can have subdirectories, but should not use that directory for anything else. That makes it easy to transfer all your genealogy images in one go.
The different GEDCOM versions are different versions of the same standard, with new versions improving on previous versions. So, it is generally best to use the latest version of GEDCOM. When a new version has just been introduced, it may not be supported by your favourite genealogy applications yet, and you may have to settle for the one-but-latest version. Encourage developers to use the latest version by asking for it.
The current GEDCOM version is GEDCOM 5.5.5, introduced in 2019 CE. GEDCOM 5.5.5 succeeds GEDCOM 5.5.1, which has been the standard since 1999 CE.
GEDCOM 5.5.5 does not introduce big new features, it solves issues with the standard itself instead. The overall technical difference between GEDCOM 5.5.5 and GEDCOM 5.5.1 is that GEDCOM 5.5.5 is considerably simpler and stricter than GEDCOM 5.5.1. Where GEDCOM 5.5.1 has multiple ways of doing things, GEDCOM 5.5.5 has one way of doing things.
For users, the difference between GEDCOM 5.5.5 and 5.5.1 is one of quality. Simply put, GEDCOM 5.5.5 is a better GEDCOM. A GEDCOM 5.5.5 file is a GEDCOM 5.5.1 file done right; the right character set, structured addresses, no obsolete or deprecated stuff, and so on. .
GEDCOM 5.5.5 is the most compatible GEDCOM version ever.
GEDCOM 5.5.5 and 5.5.1 files are so compatible that if your favourite product is not able to import GEDCOM 5.5.5 yet,
changing the version number of the GEDCOM 5.5.5 file to 5.5.1 will typically do the trick.
This ability to downgrade a GEDCOM 5.5.5 file to a GEDCOM 5.5.1 file is a deliberate feature of GEDCOM 5.5.5, and GEDCOM 5.5.5 only.
You can downgrade GEDCOM 5.5.5 file to 5.5.1 by changing the version number, you cannot upgrade a GEDCOM 5.5.1 to 5.5.5 that way. Because GEDCOM 5.5.5 files are higher quality GEDCOM files that follow stricter rules than GEDCOM 5.5.1, merely changing the version number of a GEDCOM 5.5.1 file to 5.5.5 does not get you a GEDCOM 5.5.5 file. If you try it anyway, the ostensible GEDCOM 5.5.5 you created is practically sure to be rejected as not up to GEDCOM 5.5.5 standards.
GEDZIP is related to GEDCOM, but not part of GEDCOM. GEDZIP is not tied to any particular GEDCOM version either, but is designed to be used with GEDCOM 5.5.1 and later. GEDZIP is a companion specification to the GEDCOM specification, which specifies how to bundle multimedia with a GEDCOM file. The latest GEDZIP specification is available from the same page as the GEDCOM specification.
Early versions of GEDCOM were created by FamilySearch, and the copyright is owned by their parent company, the LDS
(The Company of the President of the Church of Jesus Christ of Latter-day Saints).
Sadly, not all the early versions are available anymore.
The versions that are available, are available for free download.
Copyright of the GEDCOM 5.5.1 Annotated Edition and the GEDCOM 5.5.5 specification is owned by Tamura Jones. Those specification are available for free download from this site.
The GEDCOM 5.5.1 specification was released on 2 Oct of 1991.
For more than twenty years, the title page claimed it was merely a draft, while it wasn't; FamilySearch themselves used its new features in Personal Ancestral File, and thus forced others vendors to do the same. On 15 December 2019 FamilySearch finally admitted that GEDCOM 5.5.1, not by issueing an erratum, as they should have done, but by re-releasing the GEDCOM 5.5.1 specification with a modified release date, as if it was new document, and that has created confusion. The GEDCOM 5.5.1 release date is still 2 Oct 1991.
For an detailed discussion of this issue, refer to these two articles: GEDCOM 5.5.1 isn't a Draft (2014) and FamilySearch GEDCOM 5.5.1 Fixed (2019).
GEDCOM X is not GEDCOM.
GEDCOM X is a proprietary standard of FamilySearch. The name GEDCOM X is misleading, as it isn't GEDCOM at all; FamilySearch X would be a much better name.
Historically, GEDCOM X is one of multiple FamilySearch attempts to create a GEDCOM replacement, in chronological order: GEDXML (2000), GEDCOM XML (2000) and GEDCOM X (2011).