There are three main USB specifications that USB flash drives can connect through: 1.0, 2.0 and 3.0. Each specification publication allows for faster data transfer rates than the previous version. There have also been several prereleases and various updates in addition to these three versions.
USB 1.0 was released in January 1996. It was available in two versions:
USB 1.0 low-speed: Provides a data transfer rate of 1.5 megabits per second (Mbps).
USB 1.0 high-speed: Has a data transfer rate of 12 Mbps.
Version 1.1, an update that fixed various issues in 1.0, was released in September 1998 and was more widely adopted.
USB 2.0, also known as Hi-Speed USB, was released in April 2000. It was developed by the USB 2.0 Promoter Group, an organization led by Compaq, Hewlett-Packard (now Hewlett Packard Enterprise), Intel, Lucent Technologies, Microsoft, NEC Corp. and Philips. USB 2.0 features a maximum data transfer rate of 480 Mbps. This boosted performance by up to 40 times. It is backward-compatible so USB flash drives using original USB technology can easily transition.
USB 3.0, also known as SuperSpeed USB, was introduced in November 2008. The first 3.0-compatible USB storage began shipping in January 2010. SuperSpeed USB was developed by the USB Promoter Group to increase the data transfer rate and lower power consumption. With SuperSpeed USB, the data transfer rate increased 10 times from Hi-Speed USB to 5 Gigabits per second (Gbps). It features lower power requirements when active and idle, and is backward-compatible with USB 2.0. USB 3.1, known as SuperSpeed+ or SuperSpeed USB 10 Gbps, was released in July 2013. It bumped up the data transfer rate and improved data encoding for higher throughput.