Bridge networking is a method of connecting virtual machines to the external network by creating a virtual bridge between the physical network interface card (NIC) and the virtual network interface card (VNIC) of the virtual machine. The virtual bridge acts as a switch that connects multiple VNICs to the physical NIC of the host machine. This allows virtual machines to communicate with other virtual machines in the same KVM network setup and the external network as if they were directly connected to the physical network.