The Remote NDIS based Internet Sharing Device (often abbreviated as Remote NDIS or RNDIS) is a device driver used by Windows to enable Internet sharing or network connectivity between a host computer and a mobile device (such as a smartphone, tablet, or other device) over a USB connection.
RNDIS is typically used for scenarios where the mobile device acts as a network adapter, allowing the host computer to access the internet via the device's mobile data connection (or vice versa). This is commonly seen when connecting Android or Windows phones to a PC for features like USB tethering.