FamilySearch is the largest genealogy organization in the world. Millions of people use FamilySearch records, resources, and services each year to learn more about their family history. The site is free for everyone to use.
User Submitted Genealogies is a set of lineage linked conclusion trees provided to FamilySearch by users. This data comes from the Ancestral File, the Pedigree Resource File and other user submissions.
'Ancestral File' and 'The International Genealogical Index' are, probably, the most widely used genealogical reference sources. Unfortunately, they are also two of the most common sources of erroneous information.
Free WIKI style website that is organizing all the IGI's batch numbers for the entire country of Mexico by state, town and year. Bilingual site also explains how to use batch numbers more effectively in searches.