I was wondering, how do large companies handle user accounts and allow different applications to access them.
For example, My site will have the main site which users will use to register accounts, a forum and a standalone desktop application.
How do I go about unifying these 3 systems so that one user can log in to all 3 systems using the same account.
Maybe they are using LDAP (or operating system specific directory service i.e. Active Directory)?
Basically what you do is keep all the information about users in LDAP directory and then configure other software to use LDAP. Many opensource projects allow to authenticate by LDAP.