Currently, there are four different versions of USB 3.2, two types of USB 3.1 and many connector types and power specs. This has resulted in immense confusion among computer users. Though not perfect, the new standard seeks to simplify the connection process.

The USB4 standard includes Thunderbolt 3, a development that was fast-tracked when Intel contributed Thunderbolt 3 royalty free to the USB standards group. This is expected to make it easier and cheaper for computer manufacturers to produce devices using the technology. It should also alleviate much of the confusion between USB and Thunderbolt 3 connectivity. Both technologies now use the same USB Type-C connector.

The new USB4 standard includes a 40Gbps maximum speed, compatibility with Thunderbolt 3 devices and better resource allocation for video. This means when using a USB4 port to move both video and data at the same time, the port will allocate bandwidth accordingly, making video transfer more efficient.

Since royalty payments to Intel will end, there is a better chance of mass adoption for USB4. However, there’s a catch that could end up being a monkey wrench in the transition. Thunderbolt compatibility is not a required part of the USB4 standard, so computer manufacturers don’t have to include it.

However, USB Promoter Group CEO Brad Saunders anticipates that most computers with USB4 will be made to work with Thunderbolt 3. “We do expect PC vendors to broadly support Thunderbolt backward compatibility, because most of what they need is already built into the USB 4 design,” Saunders said. “It’s based on the same technology, so we do anticipate a high rate of adoption there.”

In addition to Thunderbolt 3, USB4 will offer backwards compatibility with earlier USB standards, including USB 3.2 and USB 2.0. However, the advantages of the USB4 protocol as a whole are constrained somewhat by cabling. The USB-C connector includes a variety of speeds and power requirements. There is not yet a labeling standard. This could still make cable selection by users problematic.

While Apple is already an adopter of Thunderbolt 3, the change will help with the creation of more accessories that will work at the higher connection speeds and have support for the standard, in part due to it becoming more widely available. Also, Intel's integration of Thunderbolt 3 into future processors, including "Ice Lake" chips announced earlier this year, will help further that support.

USB4 follows after the 2019 debut of USB 3.2 Gen 2x2, which recently underwent a somewhat confusing name change. That specification will be an upgrade from USB 3.1, now known as USB 3.2 Gen 2, doubling the bandwidth from 10Gbps to 20Gbps.

Over 50 companies are actively participating in the final stages of review of the draft specification, which is expected to be released this year in final form. Coincident with the release of the USB4 specification, the release of an updated USB Type-C specification will be made to comprehend USB4 bus discovery, configuration and performance requirements.

The USB Promoter Group is comprised of a large group of computer manufacturers.