This file is used for holding genealogy data, and is most typically called a GedCom file (short for genealogy data communications). Most software applications made for performing genealogy work (or even just basic family trees) are capable of working with GedCom files and they can generally be used on all platforms. Note however that some companies have made proprietary extensions to the GedCom format, so transfers from one software application to another are not completely guaranteed to be safe.