Opus is a lossy audio coding format developed by the Internet Engineering Task Force (IETF) and standardized as RFC 6716. It is designed for efficient encoding of speech and general audio at a wide range of bitrates, from very low bitrates suitable for voice over IP (VoIP) to relatively high bitrates for music. Opus incorporates technologies from two distinct codecs: SILK, developed by Skype, and CELT, developed by Xiph.Org Foundation. By combining these technologies, Opus provides excellent audio quality and low latency, making it suitable for both real-time communication and stored audio applications. It supports constant bitrate (CBR), variable bitrate (VBR), and average bitrate (ABR) encoding modes. Opus is royalty-free and open-source, making it a popular choice for web audio, streaming, and other applications where efficient and high-quality audio encoding is required. Its adaptive nature allows it to perform well across a variety of network conditions and hardware platforms.