The concept of identity is fundamental to every human inhabited environment. We are not "The Borg", we participate in society as individuals, we contribute to the whole, both as consumers but also as creators, with time, effort, ideas and beyond the philosophical debate of "who am I", from a practical standpoint, the identity is nothing more than a reference based on which all these deeds and debts can be uniquely attributed.
Probably the least understood aspect of authentication is that it can be performed in different parts of the networking protocol stack and like every other aspect, each has advantages, disadvantages and great deal of confusion. To understand the distinction, let's start by looking at a few examples which are fairly familiar but we don't really look at them as authentication in the normal sense.
Unauthenticated DeviceGet Id+