Changing Temperature, Changing Density. Most matter increases in volume when it gets hotter. For example, if an iron rod is heated, it will get longer and fatter and its density will decrease. This happens because the mass of the rod stays the same, but its volume increases. The increase in the volume of matter with increasing temperature is called expansion. When cooled down, most matter decreases in volume and increases in density. This decrease in volume is called contraction.
USB-C also builds on the new USB 3.1 standard so to all intents and purposes is the connection type that brings in the new power and speed advantages of USB 3.1. USB-C is still backwards compatible with existing USB variants, but that of course requires adapters.
USB 2.0 is a version of the USB standard, and probably the most widely available one. USB 1 is old and never really caught on. USB 3 is new, very high performance, and is only just becoming widely available. It is 10 (USB 3.0) or 20 (USB 3.1) times faster than USB 2. USB Type C is new connector for USB. Traditionally USB used a Type A connector on the Host (computer) and a Type B connector on the peripheral (phone etc), There were several variants of the Type B, of which the most familiar is the Type B micro used on most mobile phones. Both Type A and Type B had variants to carry the extra conductors for USB 3.