Courses/CS 461/Museum of unintended consequences/USB port as power supply and HTML for formatting
From CSWiki
Once a mechanism has been established in the world, people will use it for their own purposes. Two examples (not necessarily negative) are the use of the USB port as a power source and the use of HTML for formatting.
I'm in a hotel room which supplies a wireless internet connection. But this computer I'm using doesn't have a wireless capability. For people like me the hotel supplies a bridge—in this case an ASUS WL-330 bridge. This little wireless receiver, which plugs into the ethernet port on my computer, plucks a wireless signal out of the air, which it send to the ethernet card. The bridge requires a source of power. There are two options. Plug it into the wall with an adaptor, or plug it into the computer's USB port.
I don't know the history of USB ports. My guess is that power was made available through that port with the intention of supporting USB devices that need the power. I doubt that power was intended to be used by a device that didn't otherwise use the USB port. But there is nothing to stop a manufacturer from using the USB port as a power source. That's exactly what the ASUS bridge does.
HTML is the language of web pages. It was intended originally to enable page developers to describe the semantics of a web page. It was explicitly not intended for formatting. The idea was that the semantics (of a tag such as "<em>") describe an intended meaning ("emphasis"). It was then supposed to be up to the browser to render that meaning however it chose.
But people quickly determined how browsers actually rendered tags, and they came to use and then depend on that rendering. In addition, some HTML tags were formatting oriented. So people used HTML for formatting. CSS was intended to extract the formatting aspect of HTML to a formatting language. But that was only partially successful. People still use HTML for page formatting.
Neither of these unintended uses is terrible. They do illustrate, though, that once a mechanism has been created in the world, it may be used for all sorts of things that were not in the minds of those who created and installed it.
