USB Full Form, What is USB?

USB full form Universal Serial Bus.

The “Universal” means that the bus itself, and controllers for the bus don’t really care about what the data is, and only concern themselves with transmission of the data, and capabilities of hardware on both ends of transmission. RS-232 and LP both tended to bog down hardware on having to do VERY specific things with their data and how it is communicated, whereas USB is designed to abstract that through controllers that just want to know what’s going in and going out, simplifying the addressing and signaling requirements of hardware and driver designers significantly as they can just ignore signal implementation details.

The “Serial” is because the data is transmitted one piece at a time. This may seem like it would be slower than a parallel bus, and in theory it would be, but one of the biggest flaws in a parallel bus is that hardware has to be designed to input and output each bit on its own line, making it more complicated to design and more expensive in the end. Serial interfaces, especially USB, are very fast now despite having to shift bytes one bit at a time, normally.

The “Bus” is, well, because it’s a bus. It’s a common signal interconnect between hardware used to send and receive data. What’s nice about USB is that it’s a bus that extends itself externally from the computer in an addressable, tree-like manner, meaning multiple devices can connect via one physical port on the machine, and there should be no conflict. Arguably the old serial or parallel connections are not buses, as they weren’t really addressable beyond what port on the computer is used, though in theory a device and device driver could be written for those to make a sort of bus-like protocol. Typically the old standards were designed with the idea that ONE device used that connection and thus every signal going in and out was meant for that one device, which to me means they weren’t bus standards.