The Microsoft Network Adapter Multiplexor Driver is a Windows driver that enables network adapter teaming or NIC bonding. It allows multiple physical network adapters (such as Ethernet cards) in a computer to be grouped together into a single logical network adapter. This is often used to increase network performance, improve redundancy (failover), or enhance reliability by providing load balancing and failover capabilities.

This driver is typically used in business or enterprise environments where multiple network interfaces are needed for greater network throughput or for high availability configurations (such as in server environments). For example, if you have two network adapters installed in your machine, the driver can combine them into one logical adapter to optimize network traffic.