Five years ago, I imagined a website that would show how people were connected to each other in real life, so I built a prototype called ­Friendster. I decided that one of its central features would be a friend confirmation process. When you wanted to add someone as your friend, an e‑mail notification was sent with your request. If–and only if–the person approved your request, you were both listed as each other’s friends. Five years later, I am paying the price for this innovation as I face an avalanche of friend spam. I get several friend requests per day from Friendster, MySpace, and Facebook, and also from social-media services such as Yelp, Flickr, and Pownce.