info about USBs

Since its release in 2000, USB 2.0 has made its way in almost every device imaginable… computers, laptops, tablets, phones, cameras, storage devices and even bitcoin miners. While it has enjoyed tremendous popularity for over a decade, its successor USB 3.0 has been gaining rapid adoption among newer devices.

On paper, USB 2.0 is capable of transfer speeds of up to 480 Mbps while USB 3.0 caps out at 5,000 Mbps. This would suggest that USB 3.0 is at least 10 times than USB 2.0, but we all know these figures are meaningless unless it’s backed up by real world tests.
Real world speed tests done by many trusted brands have all led to similar results: USB 3.0 is about 3 times (2.5 times to 3.5 times) faster than USB 2.0. While this falls short of its marketing claim, 3 times faster is still a significant speed boost.
However, most articles fail to mention one very important point: Not all devices will benefit from USB 3.0’s superior transfer rates. Yes, external hard drives and flash drives will be able to take full advantage of USB 3.0’s speed boost. USB 3.0 mobile phones and tablets are also 2 to 3 times faster when transferring large files from their internal memories.
But for other USB devices such as external optical drives, keyboards, mice, webcams, printers, speakers, network adapters etc… there is little performance difference between USB 2.0 and 3.0.
A USB 2.0 port is able to deliver 0.5 A of power while USB 3.0 is able to output 0.9 A. This means two things: USB 3.0 devices are able to charge faster and USB 3.0 ports can support more power-hungry devices.
Samsung’s Galaxy Note 3 is the first phone in the world with a USB 3.0 port, making it ideal for comparing USB 2.0 and USB 3.0 charging speeds.
The Note 3 was connected to a desktop computer’s USB 2.0 port and recorded the time it took for the phone battery to charge from 0 to 100%. The same process was then repeated with a USB 3.0 port and a wall charger.
Charge Time

• USB 2.0
  7 h 48 min

• USB 3.0
  5 h 8 min

• Wall Charger
  2 h 15 min

Take-home lesson: If you’re using a desktop or laptop computer to charge your devices, then USB 3.0 will save you a good chunk of waiting time. However, USB 3.0’s improved charge speed still pales in comparison to a wall charger (Note 3’s default wall charger is rated at 2.0 A).
Color is the key to telling the difference between USB 2.0 and 3.0 ports. In almost all cases, USB 3.0 ports are blue while USB 2.0 ports are black or white in color.
Standard USB cables follow the same color scheme as well. In the image below, we can see that USB 2.0 connectors are white (or black), while USB 3.0 connectors are blue in color. It is also common to find a “SS” (SuperSpeed) label on USB 3.0 cables.
As for Micro USB cables (often used with mobile phones, tablets and external hard drives), you can tell the difference between USB 2.0 and 3.0 from the shapes of their connectors – Micro USB 3.0 connectors are wider than 2.0 ones. If you look closer at the image below, you will be able to spot a “SS” label on the Micro USB 3.0 cable as well.
USB 3.0 is backwards compatible, so the short answer is yes. To make things clear and simple:
USB 2.0 port + USB 2.0 device = USB 2.0 performance
USB 2.0 port + USB 3.0 device = USB 2.0 performance
USB 3.0 port + USB 2.0 device = USB 2.0 performance
USB 3.0 port + USB 3.0 device = USB 3.0 performance

Any combination will work… but to take advantage USB 3.0’s improved speed and charging, you’ll need 3 ingredients: USB 3.0 port, USB 3.0 device and USB 3.0 cable.