The fifth component to the perfect cup is the size of grind. What type of grind do you have? Does it match the brew time? The size of the coffee grinds must match the brew time so as to get optimal extraction.
Coarser grinds require a longer brew time because the water will take longer to extract the solubles from the coffee. Finer grinds, on the other hand, require a shorter brew time. As more surface area of the coffee is exposed to the hot water, a quicker extraction of solubles occurs. Espresso is a prime example. By choosing an appropriate grind, you can control the bitterness, astringency, acid and caffeine in your finished cup.
Whether coarse or fine, a key factor is for the grind to be uniform. If your grinder produces some finer dust and some larger particles, you are going to get over-extraction and under-extraction happening. A grind of consistent size will allow for an even extraction, fully bringing out the unique flavour of the coffee.
Two common types of grinders are:
A typical blade grinder has a blade that spins at high speed to chop the whole beans. Not only does it heat the beans because of the friction, it does not provide the uniformity that is desired. Indeed, it often produces a lot of coffee dust.
Burr grinders, in contrast, provide a uniform size with less heating from friction. They work by crushing the beans between two abrasive elements.
Onto the final component: Brewing to a T: Time, Temperature, and Turbulence