Almost every coffee expert agrees: Coffee tastes better when you grind the beans just before brewing the coffee. Hot water extracts flavor more or less quickly depending on the particle size of the bean, so how finely you grind your beans impacts the flavor of the brewed coffee. In general, the shorter the brewing cycle, the more finely the coffee should be ground. A quick cycle in an espresso machine requires finer grounds, whereas a longer-steeping cycle in a French press requires coarser grounds. Some coffee makers and espresso makers have built-in grinders, but they are also available separately.
Coffee grinder types.
Blade grinders are considered an entry-level option that allows you to control the coarseness of the ground beans simply by the amount of time you run the machine. Similar to a blender, blade coffee grinders consist of a covered container with a bottom rotating blade. Less expensive than a burr grinder, these grinders may provide less consistent results.
Step up to burr grinders or burr mills for a more uniform grind. They use precision-fit discs or cones to crush coffee beans consistently. You can usually choose a setting on the grinder to control the particle size to work for your favorite coffee maker.