In computer networking, multicast is group communication where data transmission is addressed to a group of destination computers simultaneously. Multicast can be one-to-many or many-to-many distribution. Multicast should not be confused with physical layer point-to-multipoint communication.

Group communication may either be application layer multicast or network assisted multicast, where the latter makes it possible for the source to efficiently send to the group in a single transmission. Copies are automatically created in other network elements, such as routers, switches and cellular network base stations, but only to network segments that currently contain members of the group. Network assisted multicast may be implemented at the data link layer using one-to-many addressing and switching such as Ethernet multicast addressing, Asynchronous Transfer Mode (ATM), point-to-multipoint virtual circuits (P2MP) or Infiniband multicast. Network assisted multicast may also be implemented at the Internet layer using IP multicast. In IP multicast the implementation of the multicast concept occurs at the IP routing level, where routers create optimal distribution paths for data grams sent to a multicast destination address.

Multicast File Management is an encrypted multicast file transfer program, designed to securely, reliably and efficiently transfer files to multiple receivers simultaneously. Utility of Multicast File Management is distributing large files to large number of receivers, a reliable tool for data distribution over any network including satellite links (with two way communication), where the inherent delay makes any TCP based communication highly inefficient. The multicast encryption system is based on TLS with extensions to allow multiple receivers to share a common key; it has the capability to communicate over disjoint networks.