Community Notes, formerly known as Birdwatch, is a feature on X (formerly Twitter) where contributors can add context such as fact-checks under a post, image or video. It is a community-driven content moderation program, intended to provide helpful and informative context, based on a crowd-sourced system. Notes are applied to potentially misleading content by a bridging-based algorithm not based on majority rule, but instead agreement from users on different sides of the political spectrum.
The program launched on Twitter in 2021 and became widespread on X in 2023. Initially shown to U.S. users only, notes were popularized in March 2022 over misinformation in the Russian invasion of Ukraine followed by COVID-19 misinformation in October. Birdwatch was then rebranded to Community Notes and expanded in November 2022. As of November 2023, it had approximately 133,000 contributors; notes reportedly receive tens of millions of views per day, with its goal being to counter propaganda and misinformation. According to investigation and studies, the vast majority of users do not see notes correcting content. In May 2024, a study of COVID-19 vaccine notes were deemed accurate 97% of the time.