There are a number of different kinds of trust in Windows now.
1 - Kerberos transitive trust exists between domains in the same forest.
These trusts are automatically created when a domain is added to a forest
and are automatically maintained.
2 - Kerberos trust with an MIT Kerberos realm.
3 - Interforest trust (Windows Server 2003 only) are created in a GUI using
the Domains and Trusts MMC Snap-in.
4 - Down-level trust is a traditional NTLM-based trust also created using
the Domains and Trusts MMC
5 - Shortcut trust is an inter-domain (within the forest) trust which can
also be created using the domains and trusts MMC
-ds
