A US company offering online social networking services (see social media) founded in 2004 by Mark Zuckerberg. A user account is necessary to access the services, which include facilities for posting, sharing, and storing pictures, videos, and text; for online chat; for creating calendars and events; and an RSS service. With about 1.86 billion (2019) active users each month, it is one of the most frequently accessed websites in the world. However, it is often criticized for collecting users’ personal information for commercial purposes.