Wikipedia
FamilySearch is a genealogy organization operated by The Church of Jesus Christ of Latter-day Saints. It was previously known as the Genealogical Society of Utah (or "GSU") and is the largest genealogy organization in the world. FamilySearch maintains a collection of records, resources, and services designed to help people learn more about their family history. FamilySearch gathers, preserves, and shares genealogical records worldwide. It offers free access to its resources and service online at FamilySearch.org, one of the most heavily used genealogy sites on the Internet. In addition, FamilySearch offers personal assistance at more than 4,500 family history centers in 70 countries, including the Family History Library in Salt Lake City, Utah.
In the search section of familysearch.org anyone can search for records of an ancestor. Use of the family tree section is reserved for registered user. Registration is free. The family tree section allows a user to build his own family tree.
The resource is maintained to support the process of obtaining names and other genealogical information so that Latter-day Saints can perform temple ordinances for their kindred dead.