Steampunk was first mentioned as a term by K.W. Jeter, the author of Morlock Night and Infernal Devices. It began as a literary sub-genre of science fiction and fantasy and today the works of H.G. Wells and Jules Verne are also often described as Steampunk, although in the context of their time, they are entirely science fiction.
So the roots of Steampunk are in fantastic literature, from there, it has spread. Today, Steampunk has developed into a vibrant subculture found both on the æthernet and in the real world. It takes its esthetics and its philosophy (if you want to take your hobby that far) from the predominant mindset of the Belle Epoque/Victorian Age/Gründerzeit mixed with a little bit of poetry and mad scientist.
Steampunk as a subculture is therefor inherently optimistic and most Steampunks have a hands-on mentality when it comes to doing things. „Doing“ is also a big part of the subculture. Most Steampunks tinker, built or create something in one way or the other.
I for my part obviously blog about the scene and I have also created my own jewelry. Others sew, build, tinker, compose, and so on. The creativity within the scene is astounding. Just check sites like kickstarter for Steampunk related projects and find out for yourself what is going on in the scene. You can also find some examples on my blog here.
Enough now with the theory and my observations, here are some examples of Steampunk as a subculture and its influences elsewhere:
The band above is Abney Park and from their dress and equipment you get a rather good idea, what the esthetics of the subculture are. This brings us to the next facette of the Steampunk subculture.
Style and dresscode:
The style again takes its inspiration from the historical garb of the middle to late 19th century, with some weird victorian-tech items added.
Aviator goggles are also a very common item, although flying was not a common pasttime in the late nineteenhundreds. This is another venue where fantasy comes in.
Steampunk influences reach further still, the Steampunk look and full fledged Steampunk worlds complete with pseudo-Victorian social conventions can be found in an astounding range of works.
(Sky Captain belongs to the Steampunk subgenre Dieselpunk. The subculture is diverse enough to create facettes, another sign of how vibrant it is).
And of course, there is a wonderful selection of genuine Steampunk literature around these days. Poems, short stories, novels, anthologies. You can find it online and at the book store of your choice. I have by now reviewed a number of Steampunk related works:
The compilation of my reviews (I guess it is a good place to start delving into Steampunk literature).
So, I hope I have given you an idea and not too much confusion.