Espresso began with steam. In 1884, Angelo Moriondo of Turin, Italy, patented a steam-powered coffee machine and showed it at the city's General Exposition. It brewed coffee in bulk, not one cup at a time.
In 1901, Milan engineer Luigi Bezzera filed a patent for a machine that brewed single servings quickly, using a handled filter holder much like the one baristas use today. Desiderio Pavoni bought the patent, and by 1905 the machines were being manufactured in Milan for cafés.
Steam had its limits, though. In 1938, Milanese coffee man Achille Gaggia patented a system that used hot water pressure instead of steam. After World War II he introduced lever machines: pulling the lever loaded a spring that drove a piston, pushing water through the coffee at high pressure. The cup came topped with a creamy layer Gaggia advertised as natural "crema."
In 1961, the Faema E61 swapped the lever for an electric pump delivering a steady nine bars of pressure, still the standard today.
A hand-pumped travel espresso maker brings the story full circle: once again, it's your own arm, not steam or a motor, that builds the pressure.