NDIS includes a protocol manager that accepts requests from the network driver (at the transport layer) and passes these requests to the NIC (at the data link layer). So multiple NDIS-conforming network drivers can co-exist. Also, if a computer contains multiple NICs because it is connected to more than one network, NDIS can route traffic to the correct card.
NDIS was developed by Microsoft and 3COM. Novell offers a similar device driver for NetWare called Open Data-Link Interface (ODI).