- Signal is a cross-platform centralized encrypted messaging service developed by the Signal Technology Foundation and Signal Messenger LLC.
- The non-profit Signal Foundation was launched in 2018 with initial funding of $50 million from Brian Acton.
- It uses the Internet to send one-to-one and group messages, which can include files, voice notes, images and videos. It can also be used to make one-to-one and group voice and video calls.
- Signal uses standard cellular telephone numbers as identifiers and secures all communications to other Signal users with end-to-end encryption.
- Between 12 and 14 January 2021, the number of Signal installations listed on Google Play increased from over 10 million to over 50 million.
- On 15 January 2021, due to the surge of new users, Signal was overwhelmed with the new traffic and was down for all users.
- The service was later restored.