USB 1.1 carries data at the rate of 12 megabits per second, which is sufficient for "medium to low-speed peripherals". This broad category includes some old telephones; digital cameras; modems; keyboards; mice; digital joysticks; some CD-ROM drives, tape and floppy drives; digital scanners and specialty printers. USB's data rate also accommodates MPEG-2 video-base products, data gloves and digitizers. USB 1.1 can also provide an interface for Integrated Services Digital Network (ISDN) and digital PBXs. USB 1.1 is largely legacy now, operating on old versions of computer operating systems and old peripherals. Since USB 2.0 is backwards compatible, it is very unusual to find a device or software that is limited to USB 1.1.
USB 2.0 carries data at the rate of 480 megabits per second, about 40 times the rate of USB 1.1.This is sufficient for most modern high-speed devices, such as smartphones; tablets; newer digital cameras and camcorders; digital music equipment and MP3 players; digital readers such as the Kindle, Nook, and others; USB storage devices and external hard drives, CD ROM drives, and others; and a huge range of other products. USB 2.0 is backwards compatible with USB 1.1 devices, meaning you can plug in a peripheral device made for USB 1.1 to a USB 2.0 port. In addition, the power carrying capacity of USB 2.0 allows you to plug in non-signal products that just need power, such as USB fans, lights, can coolers, laptop coolers, and lots more, and you can use it to charge the rechargeable batteries in many portable devices.
USB 3.0 carries data at the rate of 4.8 gigabits per second, about 10 times the rate of USB 2.0 and 400 times the rate of USB 1.1. This is a newer standard, released in November 2008. The speed is usually not required for modern equipment, however it is very valuable in high-bandwidth and high-data load applications, like large-file storage; high-resolution photography and videography; complex music and audio file applications; and many newer computers and laptops. USB 3.0 is backwards compatible with USB 2.0, meaning you can plug devices made for USB 2.0 into a USB 3.0 port. USB 3.0 reduces power draw through more sophisticated power management, allowing more precisely powered products to use USB 3.0 for power and recharging.