The coffee-machine words worth understanding.

Short definitions that explain what a term changes in the cup or the ownership routine—not just what it stands for.

Brewing and temperature

Nine-bar extraction: The approximate pressure commonly targeted at the coffee puck during espresso brewing. A pump’s maximum advertised pressure is not the same thing as controlled pressure at the puck.
PID: An electronic temperature-control system that repeatedly adjusts heat to keep the brew temperature closer to its target.
Pre-infusion: A low-pressure wetting stage before full extraction. It can help the puck saturate more evenly and reduce channelling.
Thermoblock: A compact heater that warms water as it moves through a heated block. It can heat quickly, though designs vary widely in stability and steam performance.
Thermocoil: A heating design that passes water through a heated coil. Like thermoblocks, its real performance depends on control, power and implementation.
Dual boiler: Separate boilers for brewing and steaming, allowing both jobs together with independent temperature demands.

Portafilter: The handled filter holder locked into an espresso machine. It contains the basket and prepared bed of ground coffee.
Burr grinder: A grinder that crushes beans between two shaped burrs. The adjustment range and consistency matter more than simply having burrs.
Dose: The mass of ground coffee used for a brew, normally measured in grams for espresso.
Dialling in: Adjusting grind size, dose and yield until the coffee extracts at the desired balance and strength.
Retention: Coffee left inside a grinder after grinding. Higher retention can mix older grounds into the next dose.
Channelling: Water finding weak paths through the coffee puck, producing uneven extraction and a mixture of sour and bitter flavours.

Microfoam: Glossy milk containing very small bubbles, fluid enough to pour and suitable for flat whites and latte art.
Steam wand: The pipe that injects steam into milk. Manual wands require positioning and timing; assisted wands may control temperature or texture.
Milk carafe: A removable container and frothing path used by automatic machines to dispense milk into the cup.
Flat white: A compact milk drink built on espresso with a relatively thin layer of silky microfoam rather than a tall cap of dry foam.

Backflush: A cleaning cycle that reverses water and cleaner through parts of the brew circuit on machines designed for it. Not every machine supports backflushing.
Descale: Removing mineral deposits caused by water. Frequency depends on hardness, filtration and use.
Brew group: The part of the machine where brewing occurs. On some bean-to-cup machines it is removable for rinsing; on others it is serviced internally.
Water hardness: The concentration of minerals such as calcium and magnesium. Harder water generally increases scale risk.

Put the terms to work

The comparison table lines up heat system, grinder, milk, dimensions and workflow for every indexed model.