Charcuterie is the practice of preserving meats through various methods. Now it is commonly used because of the flavors established through the preservation techniques.
There are many ways to preserve meat but the most common are:
Curing through salt, such as with bacon, pancetta, and lox
Curing through drying, such as salami and prosciutto
The meat can either be cured whole, like prosciutto or bacon, or be chopped or ground before curing. Often times the chopped or ground meat will be seasoned, mixed with fat, and put into a casing before the curing or drying, such as salami or other sausages.
Another common preservation technique is through cooking and preserving in fat. This is commonly used with confits and rillettes. The most common product preserved this way is probably duck confit, which are duck legs slowly cooked in duck fat, then cooled in the fat.
Another part of charcuterie is the use of "scraps" that would otherwise go to waste. One of the most popular ways to use these is through chopped servings such as pates and terrines. The meat is usually chopped or ground, seasoned and then cooked in a dish. It is then chilled and usually served cold.