USB-C is 24-pin double-sided (reversible-plug) connector. That means, the connector does not have any up or down orientation. It just needs to be align against the port in order to connect to host or device. USB Type-C standard was first introduced by Implementers Forum in August 2014.
USB-C connector is popular in computing industry for connectivity and power. It is even being referred as next-generation industry standard for battery charging, data transfer and video. New models of laptops by key manufacturers are extremely thin, for instance MacBook has already touched thinness of 13.1mm. At this thinness, it is hard to manage space for USB port socket of Type-B and Type-A connector. Therefore, in future USB Type-C connector will be instrumental to make even more thinner laptops and tablets.
In 2015 Apple has released its first Macbook Air with USB-C port. It has no other port except headphone jack; one USB-C port for charging, data transfer and video output. Obviously, this has helped Apple to manage thinnest possible notebook with a clean design. But there are few downsides as well; you can either use it for charging or connect peripheral accessories e.g. display MDHI/VGA etc. Also, structurally it is different from Apple's typical magnetic DC charger and does not protect MacBook from damage in case of accidental pull out of socket.