How To Make A Trigger Refer To The Current Record

I have a table full of items that have a "date_updated" field. I'd like this field to be set to GETDATE() whenever a record is updated. I've got this trigger:

CREATE trigger tr_cp_shiptos_u on dbo.cp_shiptos for update as
update cp_shiptos set date_updated = GETDATE()

Problem is, of course, there's no WHERE clause..yet. I don't know how to refer to the record that was updated.... for example:

CREATE trigger tr_cp_shiptos_u on dbo.cp_shiptos for update as
update cp_shiptos set date_updated = GETDATE()
where shipto_id = @THIS_ID

I imagine there's some kind of builtin variable or something like that. How is this done?

Thanks in advance.