By far and away, my favourite social network is LinkedIn. I respect LinkedIn because its user base sees LinkedIn’s core usage so differently. Some see it as a recruitment tool. Others see it as a sales tool. Others see it as a high quality content tool.
LinkedIn has transformed recruitment and networking. When was the last time you spoke to someone and they said “If only you’d have asked me if I knew someone at ABC company? I know Fred, and he works as a blah blah.” These conversations don’t happen any longer because users can go to LinkedIn, type in ABC company, and see how they know people there – sometimes former colleagues work there, sometimes you know someone there without realising.
LinkedIn’s freemium business model attracts users to sign up for free, which makes it more useful to its premium members who want higher quality search and targeting.
Unfortunately the endorsements feature is not assured, for instance you don’t need to have worked with someone to rate a specific skill, and I think this devalues user profiles.
To see more information about LinkedIn, directly from its CEO Jeff Weiner, spend 20 minutes watching this video. The next ten years is from 15 minutes onwards, but the first 15 minutes are also worth watching: