Theora is a free and open-source video compression format developed by the Xiph.org Foundation. It is designed to provide high-quality video streaming and playback while maintaining a low file size, making it suitable for various applications, including web video. Theora is based on the VP3 video codec and is often used in conjunction with the Ogg container format. It supports a range of resolutions and bitrates, allowing for flexible video quality. Theora is compatible with many media players and web browsers, promoting accessibility and ease of use for developers and users alike.