Unique IDentification

I don't know how I missed this, but the Global ID (GUID) field in ArcGIS gives you a hands free way to add unique ids to features. The Add Global IDs tool will create the field and populate it with the ID. The GlobalID will stick with the features as you edit or join or export or clip or whatever. This will allow you to trace back and maintain relationships.

I will start using this in everything. No more staring at the attribute table to see what I can combine to make a Unique ID.