LinkedIN - why is it useful to me?
LinkedIN has been around for quite some time, and I have been recommending it from quite the beginning. I have told why I use it to many people personally, but apparently never wrote it down.
When I recommend it in my training classes there are still many people who don't use it and who don't understand why would they need it. Then others come to my aid and "explain": "LinkedIN is the Facebook for job finding". At first I found this description trying to diminish the value of LinkedIN, but in the end it is a reasonable short description.
Unfortunately many people, including me, see Facebook as a major time-sink with very little value, while I find LinkedIN reasonably useful. Worth the effort.
The "selling point" of Facebook is that it allows you to keep in touch with "old friends".
For me one of the "selling points" of LinkedIN is that it allows to get business and job-related help from old co-workers and old acquaintances, even if we have never been "friends".
The situation: Down the road 2 years from now you are looking for a new job. You look around and find a few open positions that interest you. You could send in your CV, but it will be among the hundreds or thousands of other CVs in the pile. If you could locate someone you know, who works in that company, you could have quite some advantage over the people who just send in their CV.
How will you find out if among the hundreds of people you've encountered in your life, if any of them works there or if any of them knows someone who works there?
You could ask a few of your friends if they might know someone there, but how many will you ask? 5 people? 10 people? Instead of that you could be in direct LinkedIN contact with a few hundred people - both from your private life and from your professional life. Then you could search for the name of that company you are looking at and LinkedIN will list you the people among your contacts, and among the the contacts of your contacts who work there, or who worked there earlier. Now you know exactly who to ask for help. You can send them an e-mail, or pick up the phone and ask for that help.
All that without the need to share pictures of your family with any of these people as would be expected on Facebook.
CV
Another value of LinkedIN is that it provides you a skeleton to write your CV and keep it up-to-date. Having it publicly available has the disadvantage of not allowing you to emphasize different things to different readers, but I think most of the people don't do that anyway.