As you begin your journey into the world of espresso, it's not uncommon to feel bombarded by new words. This humble vocabulary list is offered as one place to begin learning.  It is certainly not an exhaustive list of terms you may encounter. However, we hope you find it useful.

Arabica (Coffea Arabica) A species of coffee indigenous to Ethiopia. It is believed to be the first species of coffee to be cultivated. Arabica has grown in southwest Arabia for over 1,000 years. Another commercial coffee species is the Coffea canephora or Robusta.  Arabica is considered to produce better coffee than the Robusta. Espresso is made from the Arabica bean.  

Barista  Italian term for a skillful espresso bartender.

Blend  Coffee mixture containing two or more varieties of single-origin coffee beans. 

Bottomless Portafilter (a/k/a naked portafilter or crotchless portafilter) A bottomless portafilter is a portafilter with the spouts removed.  It's only functional purpose is to hold the filter basket in place. A bottomless portafilter is an excellent training tool because it allows the barista to watch the espresso as it is being brewed.  It allows you to see the espresso as it flows directly from bottom of the portafilter basket. By watching the flowing stream, the barista can easily spot issues with channeling and other extraction problems.

Brew Group  The brew group is made up of the group head, the manual lever which activates the pump for the brewing process, the pressure release system, and the pressure relief valve.  The brew group is this whole assembly.  It moves the water through the machine and down through the portafilter.

Burr Grinder  Coffee bean grinder that utilizes either two flat-plate discs (flat plate burr grinder) or two cone shaped burrs (conical burr grinder) that can be adjusted to grind the coffee.  Unlike a blade grinder, a burr coffee grinder is preferred when making espresso because it's capable of producing a uniform grind size. 

Café au Lait  Coffee beverage made of one-third drip coffee and two-thirds hot frothed milk.

Caffè Americano  An espresso diluted with hot water. 

Cappuccino  An espresso-based drink comprised of 1/3 espresso, 1/3 steamed milk and 1/3 frothed milk. 

Channeling  Is the fast passage of water through a part or portions of the espresso puck. As to those portions, the espresso will be under extracted. Channeling most often occurs when tamping is unlevel or otherwise deficient. If channeling occurs, you should probably be able to see evidence of it in the spent puck.  The wet puck may have small holes in it or may not be tighlty formed. 

Crema   The reddish brown/caramel foam that forms on the surface of a freshly brewed espresso shot.   

Cup Warmer The cup warmer is located on the vented top of some espresso machines. (see the Andreja Premium) Ceramic cups are stored on the cup warmer to keep them toasty warm before serving. Not all machines have a cup warmer.

Demitasse  Small, three-ounce cup used for serving espresso.  

Doser  A spring-loaded device on specialized espresso grinders that dispenses single servings of ground coffee. 

Double Boiler The double boiler machine has two dedicated boilers: one for steaming and one for brewing.  Each boiler is independently controlled. Steaming and brewing can occur simultaneously without significantly affecting the other boiler's temperature.

Drip Tray  Cups that are awaiting freshly brewed espresso sit on the drip tray.  The purpose of the drip tray is to catch water drips and to collect liguid. Some super automatic machines use water after the brew process to clean themselves up.  This water will then exit the machines interior and flow into the drip tray. Drip trays are removable for easy clean up. 

E61 Brew Group  Features a manual pump lever and pressure relief valve. It was first introduced to the Italian marketplace in 1961.  Today it is still recognized as an industry standard because of its amazing ability to maintain a consistent 200 degree temperature. In fact, most high-end prosumer and commercial espresso machines today feature the E61 Brew Group.

Espresso  A luscious, crema capped coffee drink derived from a brewing method whereby hot water (195-205 degrees Farenheit), is forced through (at under .9 bar of pressure) a compressed bed of finely ground coffee (tamped at 30lbs. of pressure).  A single shot of espresso is approximately one fluid ounce.  

Golden Rule  A phrase commonly used to describe the ideal espresso brewing formula: Force 195-205 degree farenheit clean water at .9 bar or pressure through 7 grams of finely ground coffee tamped at 30lbs. for 20-25 seconds to yield one ounce of espresso.

Green Coffee  Unroasted coffee beans. 

Group Gasket  The group gasket is a ring made of rubber that seals the portafilter to the group head. The gasket seats into a groove that is machined into the group.  If the portafilter is leaking, the group gasket probably needs replaced.

Group Screen  Is located in the group head.  Remove the portafilter and take a look up under. You'll see a flat disc shaped peice of metal with holes in it.  During the brewing cycle, water travels through the group screen and into the gound coffee in the filter basket. The group screen is also called the dispersion screen or the shower screen.

Group Head  The group head is the metal, disc-shaped piece of brass that the portafilter locks into. The group head is sometimes incorrectly referred to as the brew group. The group head is merely one part of the brew group assembly.

Knock Box  A box used for dispensing used espresso grounds.  The used grounds are knocked out of the filter basket and into the knock box.

Latte  An espresso drink that is prepared with approximately one third espresso and two-thirds steamed milk. 

Latte Art  Technique performed to create visual designs such as leaves, apples, hearts, flowers, etc. by pouring properly steamed milk into a cup of espresso.

Manual (Piston) Espresso Machine  The manual machine was the first true espresso machine.  This machine is also the most difficult to use.   With a manual machine you fill, tamp and lock in the portafilter, just like you would with a semi-automatic.  From here, the difficulty begins. To create the extraction, you pull down on the lever handle. If you pull too fast or too slow, your shot is far from great.  

Over Extraction  A phrase used to described improperly brewed espresso. Over extraction results when too many coffee solids are extracted. The result is a strong often bitter tasting brew.  When espresso is over extracted, it has a long brew time and thin or very little crema.  To correct, increase the grind size or decrease the tamping pressure.

Portafilter  The entire assembly of the handle and the spouts.  This is the detachable unit that clamps into the group head. It holds the filter basket with ground coffee. The portafilter is sometimes called the filter handle.

Portafilter Basket  This is the small recepticle with holes in the bottom.  It holds the gound coffee and sits in the portafilter.  The filter baskets come in tripple, double and single sizes. 

Pre-infusion  Pre-infusion occurs prior to brewing. It is the brief, pre-wetting of the ground coffee with a small amount of hot water. It happens immediately before hot water exits the group head. Several super automatic espresso machines automatically pre-infuse the coffee before the brew cycle commences. 

Pressure Guage A pressure guage is designed to help monitor the boiler pressure. On a 16 cup la Pavoni manual machine, the pressure guage sits on the top left side of the machine.  Here, the pressure guage uses a needle to display the pressure reading.  Not all machines have a pressure guage. 

Pump Machine  An espresso machine that uses a pump to force pressurized water through the ground coffee.  Different machines use different types of pumps.  The Vetrano Rotary utilizes a quiet rotary pump.  The Andreja Premium has a 52 watt Ulka pump.  There is no pump in a manual machine.  With a manual machine, the operator  acts as the pump by pulling the lever down.

Semi-automatic Espresso Machine  Unlike the manual machines which need your arm to push a lever, a semi-automatic utilizes a pump to create consistent pressure for each extraction. An example of a semi-automatic machine is the Andreja Premium by Quick Mill.  A semi-automatic machine can feature a single boiler, a dual boiler or a heat exchanger. Unlike an automatic espresso machine,  semi-automatic machines allow the barista to start and stop the brew process with the flip of a lever or switch. On an automatic machine, the brew process stops at a pre-set time.

Sight Glass   A sight glass is designed to provide a quick check glance at the water level in the espresso machine boiler.  On the la Pavoni manual machines, the sight glass is tube shaped and sits on the left side of the machine. Most machines do no have a sight glass.

Single Boiler Espresso Machine  As the name suggests, a single boiler has one boiler which serves the two tasks of brewing and steaming. Since the boiler serves both purposes of brewing and steaming, you must wait while it transitions from brew to steam temperature. As a plus, however, the single boiler machine is less expensive than the HX and the dual boiler machine.

Steam Wand (Nozzle)  The metal arm or pipe on most espresso machines that delivers the steam required to steam milk. It protrudes from the side of the machine.  The steam wand should be cleaned after each use by wiping it with a damp cloth and opening the steam valve to clear out any milk that may have entered the steam tip.

Steam Tip  The steam tip is at the end of the steam wand.  It is responsible for the dispersion of steam.  A steam tip can vary in the number of dispersion holes it has, which varies the steam dispersion pattern.

Super-automatic Espresso Machine  Super-automatics are fully automatic machines with a built-in grinder and an array of other special features.  They are designed for convenience, speed and less mess.  These machines will grind a pre-measured dose of coffee beans and extract a specific amount of coffee. The used coffee grounds go into a bin inside the machine for later disposal.

Tamper  The pestle-like object with a flat or slightly convex end used to compress the ground coffee inside the filter basket.  

Tiger Striping  A phrase used to visually describe crema as it exits a portafilter. In the espresso stream, tiger striping appears when stripes of lighter, caramel-colored crema flow alongside stripes of darker crema.

Under Extraction  Describes a poorly brewed espresso where not enough solids were extracted.  When espresso is under extracted, it will brew fast and taste week. To correct, decrease the grind size or increase the tamping pressure. 

Whole-Bean Coffee  Coffee that has been roasted but not yet ground.