# What do the 3 symbols (circle, square, triangle) in the USB Type-A plug represent?

What do the 3 symbols (circle, square, triangle) in the USB Type-A plug represent? Is it power-/data-related notifications or just universal identification for USB?

• hi thanks for correcting my grammar in the question. Now it will shows exactly what i need to be clear. – ramesh6663 Aug 5 '15 at 12:41
• But i assumed Data,Voltage and Ground makes the USB bus. In symbol Arrow for Serial data, Circle for 5V, Square for Ground .And all are connected to the end point of the device to host/hub. Is it correct? – ramesh6663 Aug 6 '15 at 9:10

They don't seem to have much meaning from an electronics point of view and a few sites I checked such as Famous Logos seem to indicate it's more of an artistic impression:

Trident in the USB Logo

The USB logo was said to be modeled to mimic the trident of Neptune, the mighty Dreizack. Although the trident before may symbolize power and authority, the USB trident is more commonly attributed to the technological ‘power’ one can get from attaching the USB to the computers and other devices.

Shapes in the USB Logo

The shapes at the tip of the three-pronged spear (triangle, square and circle) in the USB logo are placed there to signify all the various peripherals that can be attached if the standard devices are used. It also denotes how interconnected the world has become, thanks to the technological innovations that the USB has imparted.

I don't have a source, but I recall an explanation when USB was new that the different shapes represent the different device types that USB could connect to. This emphasizes the universal in Universal Serial Bus.

Just as an example, USB 0.8 already supported output devices such as printers, HID devices, and I/O devices such as Zip drives.

This is just universal identification for USB.

From "Icon design recommendation for Identifying USB 2.0 Ports on PCs, Hosts and Hubs" :

"The icon (...) may be used to label any PC, host or hub USB port (...)
that supports USB 2.0 performance".


This document deals specifically with the 2.0 variant of the icon (with a plus), but it explains that icon means USB connectivity in general, not just particular plug or socket.