It's less of a social media site then something like Facebook or Instagram. You generally won't see selfies of fake girls with lattes and puppies. What you will find though, at least from most professional people, is a comprehensive overview of their education, past work experiences, and positive comments and recommendations, plus things they've shared recently to show how engaged in the market they are. Through their connections you can also see your degrees of freedom from them.. "Oh, Jim knows Mike, and I know Mike." If someone tells me they "live and breath data" and I see that they're sharing posts and news relatively often about the industry that gives me a sense of security that they're really engaged in the market they're looking to work in and not just blowing smoke in the interview, etc.
The *lack* of a LinkedIn tells me
-this person doesn't care enough to market themselves
-this person may be lacking in some tech skillsets (okay in some industry, not in this one)
-this person may have some other predilections against "social media" - which is fine, but tells me that for the team at our company may not be a good fit
*This is, of course, as others mentioned industry dependent. Career pilots, etc., probably don't get much value out of LinkedIn.. but if you work for any kind of tech, marketing, etc., company it can be a helpful asset. Granted, I've never landed a job because of it nor hired or didn't hire strictly based on that either
What do hiring managers look for, now?
So many of these social media sites make you the product now. What's a good balance between providing information and giving too much to the site?
My opinion is on LinkdIn, essentially reproduce a resume. I maintain a professional presence on ResearchGate, but that is narrowly focused anyway. Anything else (Facebook, Instagram, Weibo ) really shouldn't count anymore.
Several people who replied under you gave some good responses.. I would only add that at least in my case I make an effort quarterly to keep it accurate, fresh, and will occasionally post or share something about my line of work.. but otherwise it's basically an expanded resume or CV
**I generally, full disclosure, loathe social media and the trash generation of it that Mark "The Zuck" Zuckerberg has created (what a dick).. Instagram and Facebook have really degraded social interaction and friendships to be nothing more than a shallow competition. I don't have a Facebook, or Instagram.. I've had them in the past (got one back when they first came out around 2005) but I've since left it and my life has been better since. LinkedIn though I keep and loosely maintain for the reasons above