I get that question all the time. Really the meaning is, well, personal. My PLN is different from anyone else's, however, we all have similarities is why we have one and why it is important to us.
Recently at #ISTE10 a video was shot, interview several members of my PLN as to why they have one, how they use theirs, and more specifically, how Twitter has helped build that PLN. This is a video I will definitely be using in upcoming trainings and talks. Check it out...
Also, last Spring I got several other members of my PLN to give me the reason why their PLN is important to them and why they find theirs valuable to their professional learning.
So those are just a few examples of why a PLN. What are your reasons? Why is your PLN valuable to you? Leave some comments below.