An Americano coffee is a shot of Espresso coffee infused with hot water. The ratio of water to Espresso is 1:1 (equal amounts). An Americano coffee is as intensive as drip coffee, but has a different flavour.
Another coffee similar to the Americano is the ‘Long Black’ prepared by adding Espresso into hot water (instead of adding hot water into Espresso), which infracts (breaks up) the crema.