Facebook Messenger is a messaging application owned by Meta that allows users to send text messages, voice messages, photos, videos, and documents to other Facebook users. It was launched in 2011 and has since become one of the most widely used messaging apps worldwide.

Facebook Messenger uses end-to-end encryption for messages and calls, and also offers features such as group chat, video calling, voice calling, and the ability to send money to other users.

In addition to personal messaging, Facebook Messenger is also used by businesses for communication with customers through the Messenger API. This enables businesses to send automated messages, provide customer support, and sell products and services directly through the app.

Facebook Messenger can be accessed through the Facebook website or through a dedicated mobile app available for both Android and iOS devices. It also has a desktop app for Windows and MacOS. In recent years, Facebook has also integrated Messenger with its other products, such as Instagram and WhatsApp, allowing for cross-platform messaging.