LinkedIn is a social media platform website for professionals to use to find and apply for jobs, network with others, and discuss career advice.Because so many employers use LinkedIn for hiring purposes, it is important for job seekers to have a strong presence on LinkedIn, and use the site actively.It is free to sign up, and you'll need an email address and phone number, and a username and password.To log in, you'll need to go to LinkedIn.com and fill in your username and password. There's also a mobile app you can use on your smartphone., Login to LinkedIn to keep in touch with people you know, share ideas, and build your career., Founded in 2003, LinkedIn connects the world's professionals to make them more productive and successful. With more than 1 billion members worldwide, including executives from every Fortune 500.