How many friends do you have?

Anyone who hangs out on Facebook knows that there's a little box on the left side of each profile with a total number of friends for that person. Some people have a few friends, others dozens, and others hundreds or thousands.

But how many friends does the typical person have in real life? I thought about this question when attending the funeral of a friend recently. The funeral was very well-attended, and many of the people there would have described themselves as "friends" of the person who had passed away. She seemed to have been a "collector" of friends, and was obviously a treasured friend to many of the people who came to pay tribute to her life.

Facebook friends and "real life" friends are probably quite different. But even among real life friends, each of us has different categories of friendships. This piece from the BBC News Magazine explains:

The average number is about 150, says leading anthropologist Robin Dunbar.

It may sound like a lot, but think of your Christmas card list - 50 cards to 50 couples = 100 friends.

"It's the number of people that you know as persons and you know how they fit into your social world and they know how you fit into theirs. They are a group of people to which you have an obligation of friendship."

They usually consist of an inner circle of five "core" people and an additional layer of 10, he says. That makes 15 people - some will probably be family members - who are your central group and then outside that, there's another 35 in the next circle and another 100 on the outside. And that's one person's social world.

Click through; it's good stuff.