The "Genealogies" selection links you to the Genealogies page.
There are four huge databases included in the searches from this page. Near the bottom of the page there is a way to select which of the databases you wish to search individually.
Each of these huge databases contain millions of records. These records have been created by individuals submitting records to FamilySearch and its predecessors over the years and are commonly referred to as "user submitted records." The page contains a very short explanation for each of the resources, but you can get more extensive discussions from the FamilySearch Research Wiki. Here are some links to the Research Wiki pages about each of these resources.
The International Genealogical Index or IGI is particularly useful in finding the original Temple ordinance dates for any ordinances that were done before about 2008. Unfortunately the Community Trees Project website was discontinued when the database was consolidated with FamilySearch.org and much of the information in the Community Trees is now hard to discover.