LinkedIn is a business and employment oriented service operated through websites and mobile applications. It was established on December 28, 2002 and launched on May 5, 2003. It is mainly used in professional networks, including employers who publish positions and job seekers who publish resumes. As of 2015, most of the company's revenue came from selling access to member information to recruiters and sales professionals. As of April 2017, LinkedIn has 500 million members in 200 countries, including more than 106 million active members. LinkedIn allows members (workers and employers) to create profiles and "connections" with each other in online social networks that represent professional relationships in the real world. Members can invite anyone (whether or not they are existing members) to establish a connection. The purpose of the access control method (which requires an existing relationship or an introduction through contact with any professional) is to build trust between service members. LinkedIn participates in the EU's international safe harbor privacy principles.

The site ranks 34th most popular on Alexa Internet (June 2018). According to the New York Times, American high school students are now creating LinkedIn profiles to include in university applications. As of 2013, the website is located in the United States, providing 24 language versions, [10] including Arabic, Chinese, English, French, German, Italian, Portuguese, Spanish, Dutch, Swedish, Danish, Romanian, Russian, Turkish, Japanese, Czech, polish, Korean, Indonesian, Malay and Tagalog. LinkedIn filed an IPO application in January 2011 and traded its first shares under the NYSE stock code "lnkd" on May 19, 2011.

On June 13, 2016, Microsoft announced plans to acquire LinkedIn for us $26.2 billion. The acquisition was completed on December 8, 2016. According to SEC documents, "the transaction resulted in the payment of approximately $26.4 billion in cash merger consideration.