Asynchronous Transfer Mode (ATM) is a networking technology that transmits data in fixed-size packets called cells. Each cell is 53 bytes long, consisting of a 5-byte header and a 48-byte payload. This uniform cell size allows for efficient data transfer and supports various types of traffic, including voice, video, and data. ATM operates on a connection-oriented model, meaning a virtual circuit is established before data transmission begins. This ensures reliable delivery and quality of service, making it suitable for applications that require consistent performance, such as telecommunications and multimedia streaming.