Using Membership with Sitecore

Sitecore's authentication and user management uses asp.net membership with the membership schema in the Core database.  To use authentication in your own sites you can use this membership system yourself, or if you have your own existing membership database you want to use, or you want to implement membership on your site and don't want to use a separate database rather than keeping your users in the Core database, then it is possible to configure Sitecore to implement multiple asp.net membership databases.