Linkedln

I've been asked "What is Linkedln and what its purpose?", you hear it almost in every professional setting; whether it's in college, work, office, etc. Well Linkedln is one of the most popular social media platform that is geared towards professionals, it is like Facebook but for your career.
Linkedln is an American business and employment-oriented service that operates in websites and mobile apps. It is founded on December 28, 2002, and launched on May 5, 2003 by Konstantin Guericke, Jean-Luc Vaillant, Eric Ly, Reid Hoffman, and Allen Blue.

Now, why should you even consider using Linkedln? Well it's for people who are interested in taking their career more seriously by looking for new opportunities and to connect with other professionals.
Making connections in Linkedln is like sending a friend request on Facebook, and you can converse through private message and share your and the person you have connection with, each other's professional experience and achievements.

Although, majority of the people use Linkedln for getting back in touch with old colleagues. You can use the My Network section to find old colleagues, classmates, teachers, etc.
And it's also mainly used for using their profile as their resume. Using Linkedln profile basically represent a more complete resume.

I personally do not use it regularly but I've used it in the past to use it as a resume.