PIM Sparse Mode (PIM-SM) is a multicast routing protocol used to efficiently manage the distribution of data to multiple receivers in a network. It operates on the principle of creating a shared tree structure, allowing routers to forward multicast traffic only when there are active receivers. This minimizes unnecessary data transmission, making it suitable for applications where not all network nodes need to receive the same data simultaneously. In PIM-SM, routers use a process called "join" to establish connections with the multicast group. When a receiver wants to join a multicast group, it sends a request to the nearest router, which then communicates with the source to set up the data path. This on-demand approach helps conserve bandwidth and optimizes network resources.