Introduction:

LinkedIn is an American business and employment-oriented online service that operates via websites and mobile apps. Launched on May 5, 2003, the platform is primarily used for professional networking and career development, and allows job seekers to post their CVs and employers to post jobs. As of 2015, most of the company's revenue came from selling access to information about its members to recruiters and sales professionals. Since December 2016, it has been a wholly owned subsidiary of Microsoft. As of September 2021, LinkedIn has 774+ million registered members from over 200 countries and territories. LinkedIn allows members (both workers and employers) to create profiles and "connect" with each other in an online social network which may represent real-world professional relationships. Members can invite anyone (whether an existing member or not) to become a "connection". LinkedIn can also be used to organize offline events, join groups, write articles, publish job postings, post photos and videos, and more.

Membership:

As of 2015, LinkedIn had more than 400 million members in over 200 countries and territories. It is significantly ahead of its competitors Viadeo (50 million as of 2013) and XING (11 million as of 2016). In 2011, its membership grew by approximately two new members every second. In 2020, LinkedIn's membership grew to over 690 million LinkedIn members. As of September 2021, LinkedIn has 774+ million registered members from over 200 countries and territories.

Usage:

LinkedIn is particularly well-suited for personal branding which, according to Sandra Long, entails "actively managing one's image and unique value" to position oneself for career opportunities. LinkedIn has evolved from being a mere platform for job searchers into a social network which allows users a chance to create a personal brand. Career coach Pamela Green describes a personal brand as the "emotional experience you want people to have as a result of interacting with you," and a LinkedIn profile is an aspect of that. A contrasting report suggests that a personal brand is a "a public-facing persona, exhibited on LinkedIn, Twitter and other networks, that showcases expertise and fosters new connections." LinkedIn allows professionals to build exposure for their personal brand within the site itself as well as in the World Wide Web as a whole. With a tool that LinkedIn dubs a Profile Strength Meter, the site encourages users to offer enough information in their profile to optimize visibility by search engines. It can strengthen a user's LinkedIn presence if he or she belongs to professional groups in the site. The site enables users to add video to their profiles. Some users hire a professional photographer for their profile photo. Video presentations can be added to one's profile. LinkedIn's capabilities have been expanding so rapidly that a cottage industry of outside consultants has grown up to help users navigate the system. A particular emphasis is helping users with their LinkedIn profiles.

Criticisms:

LinkedIn has received criticism, primarily regarding e-mail address mining and auto-update. Changing the description below a member's name is seen as a change in a job title, even if it is just a wording change or even a change to "unemployed". Unless a member opts to "turn off activity updates", an update is sent to all of that person's contacts, telling them to congratulate the member on the "new job". The feature that allows LinkedIn members to "endorse" each other's skills and experience has been criticized as meaningless, since the endorsements are not necessarily accurate or given by people who have familiarity with the member's skills. In October 2016, LinkedIn acknowledged that it "really does matter who endorsed you" and began highlighting endorsements from "coworkers and other mutual connections" to address the criticism.

Security and Technology:

In June 2012, cryptographic hashes of approximately 6.4 million LinkedIn user passwords were stolen by Yevgeniy Nikulin and other hackers who then published the stolen hashes online. This action is known as the 2012 LinkedIn hack. In response to the incident, LinkedIn asked its users to change their passwords. Security experts criticized LinkedIn for not salting their password file and for using a single iteration of SHA-1. On May 31, 2013, LinkedIn added two-factor authentication, an important security enhancement for preventing hackers from gaining access to accounts. In May 2016, 117 million LinkedIn usernames and passwords were offered for sale online for the equivalent of $2,200. These account details are believed to be sourced from the original 2012 LinkedIn hack, in which the number of user IDs stolen had been underestimated. To handle the large volume of emails sent to its users every day with notifications for messages, profile views, important happenings in their network, and other things, LinkedIn uses the Momentum email platform from Message Systems. In 2014, Dell SecureWorks Counter Threat Unit (CTU) discovered that Threat Group-2889, an Iran-based group, created 25 fake LinkedIn accounts. The accounts were either fully developed personas or supporting personas. They use spearphishing and malicious websites against their victims. According to reporting by Le Figaro, France's General Directorate for Internal Security and Directorate-General for External Security believe that Chinese spies have used LinkedIn to target thousands of business and government officials as potential sources of information. In 2017, Germany's Federal Office for the Protection of the Constitution (BfV) published information alleging that Chinese intelligence services had created fake social media profiles on sites such as LinkedIn, using them to gather information on German politicians and government officials.