Finding the grind that produces the flavor you want can be a subjective process, but there's no mystery involved. The rule of thumb: The faster the brew method, the finer the grind. For example, use very finely ground coffee for espresso (which brews in seconds) and coarsely ground coffee for a coffee Press (which brews for 3 to 4 minutes).
(Left to right: Manual Drip, Auto-Drip, Espresso, Turkish grinds.) Infusion Grind (coarse):
Very coarse particles or flakes, like kosher salt. Grind this way for a cafetiere or coffee press, percolator, or vacuum pot. Ideal grind for methods with open-pore metal filters.
Manual Drip Grind (medium-coarse):
Medium particles, looks and feels like coarse sand. Will not compress. Use this grind for a manual drip brew method (a pour-over) or in an automatic drip brewer if you use a gold filter. (This slightly coarse grind will result in less sediment in your cup when using a gold filter.)
Auto-Drip Grind (medium fine):
Medium-fine particles. Looks and feels like grains of beach sand. Does not easily compress. This is the right grind for brewing in an automatic drip brewer with a paper filter.
Espresso Grind (fine):
Fine particles. Feels almost like confectioner's sugar in your hand and can be compressed with little effort. The resulting brew is heavily extracted and tastes rich and heavy. This is the correct grind for espresso and coffee prepared in a moka-pot.
Turkish Grind (very fine):
Very fine particles to powder. Feels almost like flour in your hand and can be most easily compressed. The resulting brew is heavily extracted and tastes rich and heavy. Turkish is the right grind for Turkish coffee, of for recipes where ground coffee should dissolve into solution.
K-Cup:
A K-Cup is a patented, single-serve capsule that protects our coffee from moisture, light and oxygen. K-Cup portion packs offer convenience and variety and are engineered exclusively for Keurig brewing systems.