Or, rather, the archives. This resource was built with the intention of putting all of the D&D information we have available in one place in order to eliminate the need to scour sourcebooks and homebrew references alike.
This is far from a comprehensive guide to all of the worlds that make up this place-- more just a way to make things easier for everyone to assemble characters built for these worlds. For in-depth stories and lore, there is another, separate website that will be available at some point, I'm sure.
These archives are home to every race (referred to here as folktype for accuracy's sake), class, and spell as published by Wizards of the Coast, as well as homebrew folktypes, classes, spells, and relevant lore.