The UseCases page defines a very fine grained classification of users. There should be a more general classification that makes it easier to refer to one of them if we talk about target users in discussions. The general classification here is End Users vs. Technical Persons. There's always a system where someone becomes an End User, so please don't see this as a elite classification in any way. We can also use this eye winking definition: A user once called himself a MereMortal.
Here's another useful classification from this Economist Survey:
UBS's Mr Coburn adds a demographic observation.
- analogues - Today, he says, some 70% of the world's population are "analogues", who are "terrified by technology", and for whom the pain of technology "is not just the time it takes to figure out new gadgets but the pain of feeling stupid at each moment along the way"
- digital immigrants - Another 15% are "digital immigrants", typically thirty-somethings who adopted technology as young adults;
- digital natives - and the other 15% are "digital natives", teenagers and young adults who have never known and cannot imagine life without IM (instant messaging, in case you are an analogue)