Porter is a beer style that was created in London sometime in the 18th century, but well-balanced and aromatic modern varieties do not share many similarities to the original version. Roughly defined, porter is a versatile dark ale made from dark malted barley and a hefty amount of hops.
This versatile style is usually characterized by roasted, malty flavors and medium hop bitterness. Nowadays, most porter styles are classified as brown, robust, and Baltic. It is believed that this style first appeared in London alehouses that used to store three types of beer: aged, fresh, and strong, which would then be mixed in various blends.
The name appeared because the new brew was particularly popular among the porters who carried goods around the city. By the 19th century, porter went to become the first mass-produced beer in the world that was also especially favored in American colonies, while a similar style known as plain porter was simultaneously developed in Ireland—which would later carry the name Guinness and be classified as a stout.
In the mid 20th century, porter fell out of favor, and only recently it had seen somewhat of a renaissance when craft breweries tried to reintroduce this classic style. Porters can match a wide variety of dishes, but they are best paired with smoked or grilled meat, stewes, sausages, and blue cheeses.