USB-C is a connection type standard designed to replace all USB types on the computer and device ends of future USB with a single reversible connector.
USB-C allows for peripheral connectivity of USB devices at speeds power outputs of USB 3.1 (up to 10Gbps and 20v @ 5A). This capacity is enough to provide 100w, adequate power for the majority of laptops while also supporting thinner, smaller devices. USB-C will support both the data and power needs of many devices in one of the most compact connector formats.
While having new power capabilities of USB 3.1, Type C remains electrically compatible with previous USB standards through the inclusion of extra pins. One need only use a USB-C to USB adapter in the required type for older devices (such as USB-A, B and their mini and micro versions). Thunderbolt 3 connections can be made with special cables with a bit of circuitry.
The device connectivity standard is planned to be used for foreseeable future speed grades -- a future of more compatible connections and less flipping of cable heads.