DisplayPort Alt Mode is a specific implementation of USB-C's Alternate Mode that carries a DisplayPort video signal directly over the USB-C connector. It is the most common way that laptops, tablets and phones send video to an external monitor through a single USB-C port.
Because it is a native DisplayPort signal rather than a converted one, DisplayPort Alt Mode supports high resolutions and refresh rates without extra conversion hardware, and it can share the connector's bandwidth with USB data or Power Delivery charging at the same time, which is how many docking stations and monitors both charge a laptop and display its screen through one cable.
Adapters and cables that convert DisplayPort Alt Mode to HDMI are common, since most monitors still use HDMI or DisplayPort ports rather than USB-C. See our guide to USB video output for how to set this up in practice.
