USB-C is an industry-standard connector for transmitting both data and power on a single cable. The USB-C connector was developed by the USB Implementers Forum (USB-IF), the group of companies that has developed, certified, and shepherded the USB standard over the years. The USB-IF counts more than 700 companies in its membership, among them Apple, Dell, HP, Intel, Microsoft, and Samsung.
This broad acceptance by the big dogs is important, because it’s part of why USB-C has been so readily accepted by PC manufacturers. Contrast this with the earlier Apple-promoted (and developed) Lightning and MagSafe connectors, which had limited acceptance beyond Apple products, and which, because of USB-C, are soon to be obsolete.
The default protocol used over the USB-C connector is USB 3.1, which, at 10Gbps, is theoretically twice as fast as USB 3.0. The minor wrinkle is that USB 3.1 ports can also exist in the original, larger shape; these ports (the rectangles we all know) are called USB 3.1 Type-A. But aside from on desktops, it’s much more common to see USB 3.1 ports with USB-C physical connectors.
The USB-IF has defined the USB 3.1 Gen 1 standard as meeting the same interface and data-signaling rates as USB 3.0. So, when you see USB 3.1 Gen 1, it basically works at the same 5Gbps maximum speeds as USB 3.0. USB 3.1 Gen 2, on the other hand, refers to data-signaling rates at up to 10Gbps, double that of USB 3.0, and matching the peak theoretical speeds of single-channel Thunderbolt.