USB-C or USB Type C is the latest standard for USB cables, used for both charging and transferring data. As of 2018, many of the newest laptops, phones and tablets are now adopting the USB-C connector. The plug size and style is the same as used for Thunderbolt 3, meaning that any Thunderbolt 3 cable can be used as a USB-C cable and vice versa, just note that Thunderbolt is a technology different to USB-C so devices requiring Thunderbolt 3 connection will not work with a Type C connection.
USB Type C cables use the USB3.1 version, which currently has the fastest data transfer rate of all USB versions at 10Gbps with a power output of up to 20 volts (100 watts) at 5 amps. Note that Thunderbolt 3 is capable of transferring up to 40Gbps, hence it is used on devices requiring high levels of data transfer. USB-C and Thunderbolt 3 cables are interchangeable though.