Before going into detail about the breakdown of different aspects of coffee, I thought the first useful step would be to define what coffee is and how it can be evaluated.
(Other than just being totally awesome) Coffee is essentially a combination of organic (sugars) and in-organic (salt) chemical compounds. Made from roasting the cherries of several varieties of evergreen shrubs, generally either arabica (coffea arabica) or robusta (coffea canephora), coffee has become very popular worldwide as a means of consuming caffeine.
There are many different factors that go into developing the various characteristics that can be experienced in coffee. As an organic plant, much of the flavour potential comes from the location the plant is grown (soil, temperature, humidity, altitude, etc), and thus how the plant metabolised and stored the plant sugars it creates as it grows. Then depending on the process used to harvest the cherries, further ranges of flavours can be developed natural, washed, honey, etc). Once at the roaster, it is then up to them to control how far the external and internal roasting of the cherries is taken (which is often dependant on the brew method intended on being used). Then finally, it is up to the barista as to how coarse/fine it is ground, and ultimately how the final product is prepared.
Though out this entire process many other factors such as storage, temperature, oxidization, degassing, etc, impact the experience that you have at the end of the chain.
It is anything but simple, but when done right…. it can be awesome…!