PIM Sparse Mode and PIM Dense Mode # IGMP and PIM?  

What is PIM ?

A group of multicast routing protocols is called PIM (Protocol Independent Multicast). The term "independent" refers to the fact that PIM leverages data from unicast routing protocols to create a topology rather than creating one on its own. PIM comes in a variety of forms, including PIM Dense-Mode, PIM Sparse-Mode, Bidirectional PIM, and Source Specific PIM. 

What is difference between PIM from IGMP?

Only forwarding multicast streams to the connections that have specifically requested them is possible with IGMP snooping. 

For PIM Sparse mode to function, specified selected routers must be notified of all streams going to particular multicast address ranges.