Facebook is a social networking service for individuals, groups and organisations. Users create profiles, post text, photos and video, and share them publicly or with chosen friends and groups. The service also includes Messenger for chat and calls, groups, events and Marketplace. It is available as a website and as apps for computers, tablets and smartphones, and it is delivered entirely as a hosted service: there is no self-hosted version, and the software is not open source.
Facebook was founded in 2004 and is owned by Meta Platforms, a US company that provides the service itself and runs it in its own data centres. As a US-based provider, Meta is subject to US law, which a European organisation should weigh when it publishes or processes personal data on the platform. The GDPR continues to apply to the processing of personal data of people in the EU. Users cannot run their own instance. It is therefore sensible to keep an independent channel, such as your own website, alongside any presence on Facebook.