A tabby is any domestic cat (Felis catus) that has a coat featuring distinctive stripes, dots, lines or swirling patterns, always together with a mark resembling an 'M' on its forehead. Tabbies are sometimes erroneously assumed to be a cat breed.  In fact, the tabby pattern is found in many breeds, and is a genetic landrace common among the general mixed-breed population. The tabby pattern is a naturally occurring feature that may be related to the coloration of the domestic cat's direct ancestor, the African wildcat (Felis lybica lybica), which—along with the European wildcat (Felis silvestris silvestris) and Asiatic wildcat (Felis lybica ornata)—has a similar coloration. A genetic study found five genetic clusters from tabbies to be ancestral to wildcats of various parts of the world. 
The English term tabby originates from the translation of the French phrase "striped silk taffeta", the root of which is tabis, meaning "a rich watered silk." This can be further traced to the Middle French atabis (14th century), which stemmed from the Arabic term attabiya.  This word is a reference to the neighborhood in Baghdad, Attabiy (named for Prince Attab of the Umayyad Caliphate), where such silk cloth was first made. Tabby is also comparable to the Spanish word ataviar, which means "to decorate or to dress or wear" and often implies luxurious clothing.  Usage of the term tabby cat , which means "one with a striped coat", began in the 1690s and was later shortened to tabby in 1774. The notion that tabby is indicative of a female cat may be a reference to the feminine proper name Tabby, as a shortened form of Tabitha. 
All those patterns have been observed in random-bred populations. Several additional patterns are found in specific breeds. A modified Classic tabby is found in the Sokoke breed. Some are due to the interaction of wild and domestic genes. Rosetted and marbled patterns are found in the Bengal breed.
The Mackerel tabby pattern has vertical, gently curving stripes on the side of the body. The stripes are narrow and may be continuous or broken into bars and spots on the flanks and stomach. An "M" shape appears on the forehead, along with dark lines across the cat's cheeks to the corners of its eyes. Mackerels are also called 'fishbone tabbies', probably because they are named after the mackerel fish.  Mackerel is the most common tabby pattern.
The Classic (also known as "Blotched" or "Marbled") tabby tends to have a pattern of dark browns, ochres and black but also occurs in all colors except white. Classic tabbies have the "M" pattern on their foreheads but the body markings have a whirled or swirled pattern (often called a "bullseye") on the cat's sides. There is also a light colored "butterfly" pattern on the shoulders and three thin stripes (the center stripe is dark) running along its spine. Like the Mackerel tabby, Classic tabbies have dark bars on the legs, tail, and cheeks.
The Ticked (or Stripeless) tabby pattern produces agouti hairs, hairs with distinct bands of color on them, breaking up the tabby patterning into a "salt-and-pepper" or "sand"-like appearance. Residual ghost striping or "barring" can often be seen on the lower legs, face, and belly and sometimes at the tail tip, as well as a long dark line running along the back, usually in the spine.
The Spotted tabby is a modifier that breaks up the Mackerel tabby pattern so that the stripes appear as spots. Similarly, the stripes of the Classic tabby pattern may be broken into larger spots. Both large spot and small spot patterns can be seen in the Australian Mist, Bengal, Serengeti, Egyptian Mau, Arabian Mau, Maine Coon, and Ocicat breeds.
The tabby patterns are due to three distinct gene loci and one modifier:
The agouti gene, A/a,  controls whether or not the tabby pattern is expressed. The dominant A expresses the underlying tabby pattern, while the recessive non-agouti or "hypermelanistic" allele, a, does not. Solid-color (black or blue) cats have the aa combination, hiding the tabby pattern, although sometimes a suggestion of the underlying pattern can be seen (called "ghost striping") This pattern is mostly seen in young cats that still have the baby coat. The right pattern (Classic, Mackerel, or Spotted) will reveal itself then, because that is independent of whether it is tabby or solid.
However, the agouti gene only controls the production of black pigment, so a cat with an O allele for orange color will still have the tabby pattern. As a result, both red cats and the patches of red on tortoiseshell cats will show tabby striping.
The primary tabby pattern gene, Mc/mc or Mc/Mc, sets the basic pattern of stripes that underlies the coat. Mc is the wild-type tabby gene and produces what is called a Mackerel Striped tabby. Classic tabbies are cats who also possess mc/mc, a recessive mutant gene that produces the blotched pattern.
The spotted gene is directly connected to the Mc gene; it 'breaks' the lines of a Mackerel tabby, turning it into spots. The spotted gene is dominant as well, which means a Spotted will be Sp/sp or Sp/Sp together with Mc/mc and Mc/Mc and A/a and A/A.
The Ticked tabby pattern is on a different gene locus than the Mackerel and Classic tabby patterns, and is epistatic to the other patterns. A dominant mutation, Ta / ta, masks any other tabby pattern, producing a non-patterned, or agouti tabby, with virtually no stripes or bars. If the Ticked tabby pattern gene is present, any other tabby pattern is masked. Cats homozygous for the ticked allele (Ta / Ta) have less barring than cats heterozygous for the ticked allele. When a cat of this genetic make-up is selectively bred for lack of barring and wide banding on the hair shaft, the resulting pattern is referred to as Shaded.
Since the tabby pattern is a common wild type, it might be assumed that medieval cats were tabbies. However, one writer believed this to be untrue, at least in England. Some time after the mid-17th century, the natural philosopher John Aubrey noted that William Laud, the Archbishop of Canterbury was "a great lover of Cats" and "was presented with some Cyprus-cats, i.e. our Tabby-Cats". He then claimed that "I doe [ sic] well remember that the common English Catt, was white with some blueish piednesse (i.e. white with grey parts). The race or breed of them are now almost lost."  However, most drawings or paintings of cats in medieval manuscripts do show them to be tabbies. 
Well-known tabby cats include Freya, who belongs to former British Chancellor of the Exchequer George Osborne,  and Think Think, one of two cats belonging to the President of Taiwan, Tsai Ing-wen.  One of the first mass-produced stuffed toys, the Ithaca Kitty, was inspired by a tabby cat. 
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- Oliver Lawson Dick, ed. Aubrey's Brief Lives. Edited from the Original Manuscripts, 1949, p. xxxvi.
- Kathleen Walker-Meikle, Medieval Cats (British Library, 2011).
- Walters, Simon (2012-06-23). "Chancellor George Osborne reunited with fat cat Freya who disappeared three years ago | Daily Mail Online". Dailymail.co.uk. Retrieved 2016-06-25.
- "Taiwan's cat-loving President to adopt dogs too, East Asia News & Top Stories". The Straits Times. 2016-05-27. Retrieved 2016-06-22.
- "Ithaca Kitty was a success across America". Ithacajournal.com. 2016-07-28. Retrieved 2017-03-06.
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