Finally, and very importantly, participants have identity. For example, a student has a student ID, a driver has a driving license, and a citizen has a social security number. It's obvious that there is a difference between a participant and what's used to identify a participant. And, it's really important to hold these two concepts as closely related, but separate to each other.

For example, a participant might have different identities to participate in different business networks—it might be the same bank which participates in an insurance network, and a mortgage network, but it will have different identities in these two networks. Moreover, even within a single network, a participant might have their current identity compromised, allowing them to be impersonated. In this case, their compromised identity will be revoked and a replacement issued for use by the true participant, denying the impersonator, allowing trust to be restored. Different identities, but the same participant—that's the take-away message.

It's because of this concern over impersonation that certain identities are deliberately expired periodically. For example, X.509 digital certificates have an expiry date, after which they are no longer valid. However, just because the certificate has expired, it cannot be assumed that the participant is no longer present.

In fact, it's quite the opposite. The relative permanence of a participant compared to its identity means that it can be used to provide a long-term historical reference of who does what in a business network. The consistency of identity provided by a participant over time helps us reason about the history of interactions in a business network. We could do this without the concept of a participant—just using identities, and keeping a clear head about how and when they changed in relation to each other, but it would be less intuitive.

That's just about it on the topic of participants; you're now an expert! As you can tell, participants are probably the most important thing about a business network, which is why we spent quite a bit of time discussing them. Let's now turn our attention to the objects that move between participants, namely assets.