Universal serial bus (USB) 3.0 is the third version of the USB standard for interfacing computers and electronic devices, with SuperSpeed (SS) transfer rate of almost 5 Gbit/s ten times faster than the USB2.0.
USB 3.0 connectors are distinctly differentiated from USB 2.0 by blue color-coding of the Standard-A receptacles and plugs and by the initials SS.
The USB endpoints and the four transfer types are the same whilst the protocol and electrical interface are different with a separate channel for USB3.0 traffic
USB 2.0 offers transfer rates of 480 Mbps and USB 3.0 offers transfer rates of 4.8 Gbps; ten time faster. But the transfer speeds depends on the device in use in addition to the bus type and USB ports and cables.USB 3.0 adds a new transfer type called SuperSpeed or SS, it is more similar to PCI Express 2.0 and SATA than USB 2.0
Because of its multiple advantages over USB 2.0, USB 3.0 has been improving its market share. USB 3.0 offers higher speed (up to 5 GB per second raw bandwidth), which is higher power availability (up to 900 mA per port), and better power management through more levels of power reduction when maximum power isn’t needed.
Also instead of one-way communication, USB 3.0 uses two unidirectional data paths: one to receive data and the other to transmit simultaneously (known as full duplex) while USB 2.0 can only handle only one direction of data at any time (known as simplex or half duplex)
A USB 2.0 port is able to deliver 0.5A of power while USB 3.0 is able to output 0.9A meaning two things; USB devices are able to charge faster and support more power hungry devices. USB 3.0 is compatible with all USB types before it, it just goes at the max speed of that port instead of what it is capable of.
USB 3.0 receptacles are electrically compatible with USB Standard 2.0 device plugs if they physically match. USB 3.0 type-A plugs and receptacles are completely backward compatible, and USB 3.0 type-B receptacles will accept USB 2.0 and earlier plugs. However, USB 3.0 type-B plugs will not fit into USB 2.0 and earlier receptacles. This means that USB 3.0 cables cannot be used with USB 2.0 and USB 1.1 peripherals, although USB 2.0 cables can be used with USB 3.0 devices, but only if at USB 2.0 speeds..
Color is key to telling the difference between USB2.0 and USB 3.0 ports, in most cases USB 3.0 ports are blue while USB 2.0 are black or white in color
However when users needs more USB3.0 ports on their PCs it is recommended to use external USB 3.0 hubs as an alternative