IMHO by PopopThePatriot: LINKEDIN

LinkedIn is a business and professional social media networking site designed to connect business professionals with other business professionals, as well as connect businesses with those professionals.
LinkedIn (follow on Twitter @linkedin) is considered a public, specialized network because of its focus on the particular function of business networking targeting a specific audience of business professionals (Bovée, 2014).
LinkedIn differs from public, general purpose networks like Facebook or Google+ because it is mostly used for socializing with family and the general public on a more personal, as opposed to professional, level.
How might you use this site to advance your career opportunities?
By networking with like-minded business professionals, LinkedIn offers the opportunity to showcase your experience and talents to potential hiring managers and corporations.
I have personal experience on how LinkedIn can help a career as I used LinkedIn in late 2008 to connect with former associates at Wachovia Bank (now Wells Fargo) when I moved to Des Moines, IA and was in search of work. I connected with Senior Vice President from Wachovia Training who was able to get me connected with some hiring managers in the Des Moines area.
I also learned about the job opening at my current employer through LinkedIn. This position was not posted in any of the usual job board networks like Monster, or HelpWanted.com.
Because employment at my current employer is so highly sought after, they rarely post externally, but when they do, they limit postings to specialized media sources like LinkedIn and other business networks that provide them with access to candidates with specific job skills.