Steampunk = Mad Scientist Inventor [invention (steam x airship or metal man / baroque stylings) x (pseudo) Victorian setting] + progressive or reactionary politics x adventure plot
– Jeff VanderMeer, The Steampunk Bible
Steampunk is a very relaxed genre overall, but the above equation does boil it down to the essentials. Anything can be and has been added to that equation – romance, mystery, horror, the supernatural. Politics may take a backseat to adventure, fashion and manners may eclipse the technology, history may be slightly altered or a total fabrication, but the foundation remains the same. From serious statement to total fluff, there is steampunk for everyone.
If you would like to start with the origins of steampunk, try Jules Verne’s 20,000 Leagues Under the Sea. For more serious alternative history and technology, try The Difference Engine by William Gibson and Bruce Sterling. And for some madcap adventure in a Victorian London you would never imagine, dive into The Parasol Protectorate series by Gail Carriger. Take a look at the Steampunk list on the library catalog.