Advanced Audio Coding (AAC) is a lossy audio compression standard. It's designed to be the successor to MP3, offering better sound quality at the same bit rate. AAC is widely used for digital audio broadcasting, streaming, and file-based content. It's the default audio format for YouTube, iOS devices, Android, Nintendo, PlayStation, and various other platforms and devices. AAC achieves its higher efficiency through more sophisticated encoding techniques than MP3, including improved filter bank, prediction, and entropy coding. Different profiles of AAC exist, such as AAC-LC (Low Complexity), AAC-HE (High Efficiency), and AAC-ELD (Enhanced Low Delay), each optimized for different applications and bit rates. AAC-LC is the most common profile. AAC-HE is optimized for low bit rates and is often used in streaming services. AAC-ELD is designed for real-time communication applications where low latency is critical. The format is standardized by ISO and IEC as part of the MPEG-2 and MPEG-4 specifications.