The fork, unlike knife and spoon, has not always been part of table settings. In fact, its history is relatively very recent. Although it appeared in Greece as early as the 4th century, it did not start to be generally used until the Modern Ages. Before the fork was introduced, people would largely eat food with their hands, calling for a common spoon when required. For aristocrats, though, table manners appointed that only three fingers should be used to touch the food, leaving the little and ring fingers unused.
First attempts in Italy
From the 7th through the 13th Centuries, forks were fairly common among the wealthy in the Middle East and Byzantium. In the year 1005, the byzantine aristocrat Maria Argyropoulina married the future Doge of Venice, Domenico Selvo. During their wedding celebrations she dared to refuse to eat with her hands. Instead, she had one of her eunuchs cut her food into little pieces she was able to eat with a golden fork she carried with her, fact that was considered decadent by everybody. The princess died shortly after of some disease, and this was perceived as divine punishment. The cardinal bishop of Ostia, St Peter Damian, spoke "of the Venetian Doge's wife, whose body, after her excessive delicacy, entirely rotted away." He preached extensively against this extravagant instrument, calling it both diabolic (probably due to its Devil's trident-like form) and useless, as spaghetti and macaroni were so hard to eat with it. It must be noted that forks at that time were flat and two-pointed, thus much more difficult to handle.
Hence, fork disappeared for 300 years from Italian table, until the 16th century, when it was rediscovered thanks to a renewed social interest in cleanliness. In 1533, another royal marriage, that of Catherine de Medicis with the king Henry II of France, spread the use of the fork. The Italian princess made it fashionable in the French court. She introduced the usage of each guest arriving at a dinner with their own fork and spoon enclosed in a box called a "cadena".
Use in Europe
England saw its first fork when a traveller called Thomas Coryate described its using as good manners, after one of his journeys to Italy in 1608. In the beginning, he was ridiculised and mocked, and fork seen as an affectation. "Furcifer" he was called, which means "pitchfork handler" in Latin. The clergy perceived its use as an ungodlt act, by saying that "God in his wisdom has provided man with natural forks - his fingers. Therefore it is an insult to Him to substitute artificial metallic forks for them." However, in 1633, Charles I of England declared that "it is decent to use a fork", a statement that heralded the beginning of civilised table manners. After some years, every member of the British royal family and the court possessed a fork. Its use was slowly spread among the wealthy in England, as imitating Italian habits was seen as sign of culture and refinement.
However, the way to use the fork remained a mystery revealed to only a few, well into the 18th century. Joseph Brasbridge, an English retail silversmith, wrote of his confusion in a customer's home, "I know how to sell these articles, but not how to use them." The king Louis XIV of France continued to eat with fingers or a knife for many years. Once he discovered its usefulness, though, he became the first host in Europe to provide complete sets of dinnerware for his guests, suppressing the necessity of the "cadena". He also ordered shape changes in dinner knives, such as rounding its point, as their pricking task was not needed anymore. In the 19th century, mass production and the invention of the electroplating process made metallic forks affordable to a rising middle class who wished to emulate the nobility.
The fork shape has been subject to several changes. By the end of the 1600's, manufacturers were adding a third tine to denote the old custom of eating with just the first three fingers. In Italy, Gennaro Spadaccini was the first to add a fourth tine and round its sharp points, under the order of king Ferdinand to adapt it for the eating of spaghetti. Finally, in the beginning of the 18th century, the curved fork was developed in Germany, coming out in the tool we know today. The additional tines made diners less likely to drop food, and the curved tines served as a scoop so people did not have to constantly switch to a spoon while eating.