Espresso is a concentrated beverage brewed by forcing a small amount of nearly boiling water under pressure

Pressure

Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

 through finely ground coffee

Coffee bean

A coffee bean is a seed of a coffee plant. It is the pit inside the red or purple fruit often referred to as a cherry. Even though they are seeds, they are referred to as 'beans' because of their resemblance to true beans. The fruits - coffee cherries or coffee berries - most commonly contain two...

. Espresso is widely known throughout the world.

Compared to other coffee brewing methods, espresso often has a thicker consistency, a higher concentration of suspended solids, and crema (foam

Foam

-Definition:A foam is a substance that is formed by trapping gas in a liquid or solid in a divided form, i.e. by forming gas regions inside liquid regions, leading to different kinds of dispersed media...

). As a result of the pressurized brewing process, the flavours and chemicals in a typical cup of coffee are very concentrated; so espresso is the base for other drinks, such as a latte

Latte

A latte is a coffee drink made with espresso and steamed milk. Variants include replacing the coffee with another drink base such as masala chai, mate or matcha...

, cappuccino

Cappuccino

A cappuccino is an Italian coffee drink prepared with espresso, hot milk, and steamed-milk foam. The name comes from the Capuchin friars, referring to the colour of their habits.- Definition :...

, macchiato

Caffè macchiato

Caffè macchiato , sometimes called espresso macchiato, is a coffee drink, made out of espresso with a small amount of milk.'Macchiato' simply means 'marked' or 'stained', and in the case of caffè macchiato, this means literally 'espresso stained/marked with milk'. Traditionally it is made with one...

, mocha

Cafe Mocha

A caffè mocha or café mochaAs elsewhere in coffee naming, the Italian caffè and French café are commonly found, as are the hyperforeignisms caffé and cafè, which confuse the accents. Also, in Italian, the correct spelling is Moka, used both for the city and the Moka pot. "Mocha", by contrast, is...

, or americano.

While espresso has more caffeine per unit volume than most beverages, compared on the basis of usual serving sizes, a 30 mL (1 US fluid ounce

Fluid ounce

A fluid ounce is a unit of volume equal to about 28.4 mL in the imperial system or about 29.6 mL in the US system. The fluid ounce is distinct from the ounce, which measures mass...

) shot of espresso has about one third the caffeine

Caffeine

Caffeine is a bitter, white crystalline xanthine alkaloid that acts as a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants...

 of a standard 180 mL (6 US fluid ounce

Fluid ounce

A fluid ounce is a unit of volume equal to about 28.4 mL in the imperial system or about 29.6 mL in the US system. The fluid ounce is distinct from the ounce, which measures mass...

s) cup of drip-brewed coffee, which varies from 80 to 130 mg.
Espresso is made by forcing very hot water under high pressure through finely ground, compacted coffee.