Community Trees are genealogies from specific periods and localities that have been linked according to family lineages. Many trees include associated documents and images. Each community tree is a searchable database that allows views of individuals, families, ancestors, and descendants and gives various options for printing.This is an all or nothing kind of website. If any of your ancestors happen to fall into a Community Trees collection, then you are likely to find a huge amount of information. If not, then they will not be in the collections at all. The collections on Community Trees cover wide ranging geographic areas from Australia to Iceland. They also go back to 13 B.C. for Maori Pedigree Charts and well into the 20th Century.
One valuable collection is the British Isles Families with Peerage, Gentry, and Colonial American Connections. This database was compiled from 15 reputable publications. These lines are very important because they connect to many immigrants to America. That Collection has 224,355 names.
Some of the collections are limited to a very specific geographic area, while others cover entire countries. To get into the list of collections, you need to click on the "Community Trees" link in the middle of the startup page. Here is a screenshot showing you the location of the link:
Unfortunately, you will not find a link directly from FamilySearch.org to this valuable program. I would guess that it is considered too "expert" for the average family history researcher.