The Vancouver Indy Coffee Scene

A professional who is highly skilled in coffee preparation. In Italy, a barista is a bartender who typically works behind a counter serving drinks.

An older reference to this position was called an espresso puller when extracting a shot of espresso, which consisted of pulling on a large handle with a  lot of force, forcing the hot water through the coffee grind to produce a shot. The time varied according to how long the operator pulled on the handle. With boilers and precise timers, the large handle was replaced with a button that could be timed to the exact shot time. The less elegant term was also replaced and the term became more common with the starbucks revolution of the early ’90s.

Both terms are correct for someone working an espresso bar.

Barista Amy York working her bar at Prado Cafe

A Bar is a unit of measure that is 14.503 pounds per square inch.
An espresso machine uses nine or 10 Bars of pressure to force hot water through the finely ground coffee beans. A Bar is roughly the same as the average pressure of the earth’s atmosphere, which is 1.013 25 Bar.

Author’s note:
A bar could also be in reference to an espresso bar.