Ease of Use and Broad Compatibility Drive USB Success
The nineties saw a big step in how people hook up just about anything to their computer. Before USB came out (and Apple started using it to the exclusion of other connectors), just about everything had its own connector. The picture at right shows the older PS/2 connectors for keyboard and mouse (green and purple), the serial port (yellow), and the parallel port (red) used for printers. External storage would often use variety of proprietary connectors. USB not only replaced all of this with a set of outlets you can plug just about anything into, but the connectors are easier to use.
It is practically impossible to insert a USB plug the wrong way. Doing so would require some serious ham fisting that will break the plug and socket (sockets pictured at right in orange, type A and B plugs at left, with A on the left). There are no tiny screws to deal with, which while allowing for something to wiggle loose, also means the aging boomer population isn’t in arthritic agony every time they want to exchange an external drive.
Since USB is “hot-swappable," exchanging drives, or anything else, can be done without turning off the computer, another advantage over the older connectors. Particularly when one considers the ease of use involved in plugging in a thumb drive. Here USB has benefited immensely from the ever larger capacity, ever lower price, little solid state storage sticks that many students and professionals wouldn’t be found dead without.
Speed has also become an advantage with the widespread adoption of USB. USB 2.0 will move data at 60 MB/s. USB 1.0 and USB 1.1 were limited to 1.5MB/s. You can use USB 2.0 and 1.x together, but you will be limited to the speed of the older protocol. USB 3.0 promises speeds of 625 MB/s. It is truly noteworthy that the USB connection you can use for almost anything, also connects to an external drive at a speed comparable to eSATA, which is used only for drives. Though comparable largely in the sense of molasses (60MB/s), and mercury, (300MB/s).
USB can also deliver a small amount of power to connected equipment. Items like small speakers that traditionally require a separate cable and power adapter can be run from just the USB cable. With the wide variety of USB products available, a computer-, especially a laptop-, user will often run out of USB ports. Hubs allowing several devices to use one outlet are cheaply available though.
With all of this going for USB, why do non-Apple products still include all those other, now legacy, connectors? Because…