Grind size: the degree of fineness to which the coffee beans are ground. Grind size varies from extremely fine (powder) for Turkish coffee, to coarse for plunger coffee and vacuum coffee makers. The method by which you make your coffee determines how fine a grind you should use. The key components are, the method, the coffee, the weather (in particular humidity), and tamp pressure. If you find yourself using excessive tamp pressure, yet you are grinding fairly fine, the is most likely nothing wrong with your machine. It is you coffee that is letting you down. Try a bag of Londinium Espresso and be astounded at the difference. You will not have to grind as fine, which means your grinder will last longer, and you will not have to exert much pressure with the tamp. Life is easy with Londinium Espresso.
Intensity: the term used to describe the degree of a coffee's impact on the palate. For example, Robustas are regarded as high intensity.
Maragogype: the 'elephant' bean. A variety of arabica bean almost double the normal size. Often superior in quality & priced accordingly.
Milds: a term often used when referring to washed arabica beans.
Mocha: the name designating coffee from Ethiopia and Yemen, originally shipped from the port of Mocha. Before the commencement of coffee growing in Asia and the Americas, the word 'mocha' was often used to refer to black coffee, and I believe it still is in Austria.
Pacamara: an excellent hybrid arabica bean combining Maragogype and Paca varieties and grown primarily in El Salvador.
Porcelain: the ideal material for coffee cups as it is a good insulator and does not taint the coffee.
Qishr: the Yemeni term for a brew made of dried and lightly roasted coffee cherries that have had the beans removed.
Robusta (Coffea canephora): one of the two major species of coffee, the other being arabica. Robusta accounts for 25% of all coffee consumed worldwide. Robusta beans are stronger than arabica, and much less subtle. They may be bitter, and generally have a higher caffeine content. Note: the best robustas are better than the worst of the arabicas.
Tamp: usually a flat faced metal instrument, often solid to give it some weight, used in the hand to compact the ground coffee into the porta-filter. It is a critical step in the production of espresso. If the pressure exerted is too light, air pockets will be left between some of the grinds and the water will quickly channel through these pockets as they represent the 'path of least resistance' through the coffee. It will result in underextraction, characterised by little or no crema, and any crema will be very pale in colour. If the pressure is too great it is possible that no water at all will make its way into the cup. In less extreme situations the water will eventually makes its way into the cup but the crema will be a chocolate colour, possibly with a light stain on the crema at the very end of the extraction. Both under and over extracted espresso is very unpleasant to drink, even if you have great coffee. Personally, with Londinium Espresso on board, and a moderately fine grind size, you should not be exerting much pressure with the tamp at all. I lightly tip the ground coffee into the porta-filter so it is raised up in a pyramid shape, then I lightly sweep the tamp straight across the top of the porta-filter to level it off, then I am looking to depress the level of the coffee by probably only 3mm, so it just has enough room to lock into the holder on the espresso machine. You will hear/read of people advising about 30, 50, even 70lbs of pressure. In my view this can only be the case if their grind is far too coarse, or the coffee is stale. You should only ever exert light pressure on the tamp with Londinium Espresso.