A fork was an eating utensil often made of metal. It is comprised of a handle and at least three sharpened ends on which food can be spiked. The metal tines vary in width and length, and have been sharp enough to pierce Human skin.
The utensil was used to lift food to the mouth or to hold ingredients in place while they are being cut. Food can be lifted either by spearing it on the tines, or by holding it on top of the tines.
The use of the fork was common on Earth, although other cultures have been known to use them.
In 2270, one of the practical jokes the computer of the USS Enterprise played was to supply the senior staff with forks that allowed the food to slide off before they could lift it to their mouths. (TAS: "The Practical Joker")
The rules that specify how a knife, fork, and spoon must be used in a social situation is known as utensil etiquette. Utensil etiquette is intended to prevent the utensils in use from appearing threatening. Most Humans have used a traditional style, in which they keep the fork in in their right hand throughout the dining situation. (DS9: "You Are Cordially Invited ") However some have preferred to use a hybrid utensil style when eating.
Human etiquette includes a hybrid utensil style which involves holding food to the plate with the fork tines-down, until a single bite-sized piece is cut with the knife. The knife is then set down on the plate, the fork transferred from the left hand to the right hand, and the food is brought to the mouth for consumption. The fork is then transferred back to the left hand and the knife is picked up with the right. (DS9: "Blaze of Glory")