What would the world look like if it were stuck in the late 1800s or “pre-World War I” 1900s? Steampunk is a response to that idea: Authors “freeze” society at a time when steam drives not just railroads and ships, but everything imaginable.
Electricity has not become dominant; airplanes (with fixed wings, anyway) have not been invented, and cars either have not been invented or are only owned by rich people. Instead, state-of-the-art gizmos include lighter-than-air ships (bigger cousins of the Goodyear blimps we see at NFL football games) and intelligent machinery (tank-like armored things that walk on mechanical legs).
That is what the books Airborn and Leviathan tell us: Airborn has worldwide air traffic sailing in high-altitude wind, while Leviathan has England and Germany butting heads with the help of artillery-toting “walkers” controlled by drivers inside. Society’s outlook sort of resembles Victorian England, with an emphasis on “class” (aristocrats rule – common folk serve), conformity (people think there is a “right way” to do things), and being an imperial power (making war on your neighbors helps).