OwnerID

                The OwnerID is the UserID of the person who owns the record in SFDC.  Without getting too nuts&bolts, when you look at a record through the UI you see the "Name" of the person who owns the record, but the value in the Owner field is actually the UserID.  Behind the scenes SFDC basically does a VLOOKUP against the User Object and displays the Name associated with OwnerID.  That's why when you export the raw data from SFDC you don't get the Owner Name, just their ID.  

For example the User ID starts with a 005, 00580000003I2xx, but the Owner ID starts with 00G, 00G80000001QW2m.

00G means the owner is a queue, not a user.