The story of Espresso

The history of espresso coffee starts in 1901. An Italian named Luigi Bezzera, an owner of a manufacturing company in Milan, sought out a way to reduce the coffee break times of his employees.Bezzera had the idea to introduce pressure to the coffee brewing process, reducing the time needed to brew. He called his new machine the “Fast Coffee Machine”. Espresso means “fast” in Italian. Not only did Bezzera’s espresso machine reduce brewing time it made a better cup of coffee! A faster brewing time allows for the best qualities of the coffee bean to be extracted, avoiding some of the unfavourable qualities associated with over-extraction.In 1905 Bezzera sold his espresso patent to Desidero Pavoni.
There were some disadvantages to Bezzera’s original design. Espresso tended to have a burnt flavour that was caused by boiling water and steam being forced through the coffee during the brewing process. This changed when in 1938 Cremonesi developed a piston pump that forced hot (but not boiling) water through the coffee.
It is first installed at Achille Gaggia’s coffee bar but World War II prevented further development at that time.
In 1946 Gaggia begins manufacturing a commercial piston machine. The resulting  coffee had a layer of foam on top, also known as, “crema.”
Faema launches a pump based machine. Instead of a hand operated piston the water is forced through the coffee by an electric pump. Water is taken from the fresh water supply and travels through a tube (exchanger) that is passed through the boiler and then through the coffee. This allows the water to be at the optimal temperature.

via http://www.coffeeitalia.co.uk/espresso-machine.php