Milling is the act of breaking apart the kernel of malted barley or other grain. It is done by cracking the kernel between two objects to expose the starches inside of the grain. These starches are converted into sugar by the process of mashing. When used with speciality malts (ie: Chocolate and Crystal Malts) milling improves the extraction of flavor and colouring additions. When mashing with grains the brewer will want to
 The Importance of Milling
If left unmilled the passage of water within the kernel will be extremely slow. This will cause a great deduction in efficiency and the conversion process. Also milling the grain allows the husks to act like a filter to speed up the lautering phase.
 Types of mills
There are two main types of Grain Mills on the market for homebrewers: roller and corona styles.