A French press allows the natural oils in coffee to remain present, and when properly pressed, it creates an emulsion that gives the coffee a distinct body and flavor. However, it does take some practice to use without leaving coffee grounds in the final drink or over-extracting the coffee.
A French press is a portable coffee maker consisting of a glass or metal brewing vessel and a lid with a plunger mechanism attached. The end of the plunger contains a wire strainer, and in expensive models, it may also contain a set of metal shutters to prevent spent grounds from continuing to leach bitterness into the coffee. Water and grounds are added to the vessel, and when the brewing time is complete, the plunger is depressed slowly. This slowly forces the grounds down and out of the brewed coffee, creating an emulsion with the released oil as it descends. Once the press is complete, the coffee can be poured into cups or another vessel to prevent over-extraction.
The primary disadvantage of a French press is that it can be difficult to separate the grounds from the brewed coffee. Finding the proper grind size can help prevent this problem from occurring, but many French press users simply leave a small amount of coffee in the bottom of the press and cup to avoid these bitter leftovers.