What is Friendship?
The Japanese have a term, kenzoku, which translated literally means "family." The connotation suggests a bond between people who've made a similar commitment and who possibly therefore share a similar destiny. The closer we look for the answer the more elusive it becomes. The characteristics that define a kenzoku relationship most certainly are.
1. Common interests. This probably ties us closer to our friends than many would like to admit.
2. History. Nothing ties people together, even people with little in common, than having gone through the same difficult experience. As the sole glue to keep friendships whole in the long run, however, it often dries, cracks, and ultimately fails.