ISDN, or Integrated Services Digital Network, is a telecommunications standard that allows for the transmission of voice, video, and data over traditional phone lines. It provides a digital connection, which is faster and more reliable than analog systems. ISDN can support multiple channels, enabling simultaneous calls or data transfers. There are two main types of ISDN: BRI (Basic Rate Interface) and PRI (Primary Rate Interface). BRI is typically used for home and small business connections, offering two 64 Kbps channels, while PRI is designed for larger organizations, providing up to 30 channels. This versatility makes ISDN suitable for various communication needs.