Short answers, pulled from the story.
The Oxford English Dictionary traces coat in its modern meaning to around 1300, when it was spelled cote or cotte. The word came into English through Old French and Latin cottus, with roots in a Proto-Indo-European term for woolen clothes.
Coats with sleeved, close-fitted, front-fastened construction have been found on four-thousand-year-old Tarim mummies and on the five-thousand-year-old mummy known as Otzi. The Western-style coat's origins are also linked to the Scythian nomads of the Eurasian steppes.
Before the Industrial Revolution, which began in the second half of the eighteenth century, cloth was expensive enough that coats signaled wealth and rank. Industrialization made cloth more affordable, allowing people of lower social classes to adopt fashionable outerwear. The invention of the sewing machine in the nineteenth century further increased the availability of ready-to-wear coats and jackets.
The term jacket traditionally refers to a short under-coat, with typical modern jackets extending only to the upper thigh. Coats, especially overcoats, tend to be longer, with mid-calf being the most common length. By the mid-twentieth century the distinction blurred for newer styles, and speakers of American English sometimes use the two words interchangeably.
In the early nineteenth century, Western-style coats were divided into under-coats and overcoats. The under-coat was the coat worn beneath the outermost layer; the term is now archaic. Tailcoat, morning coat, and house coat are examples of garments that fall under the older under-coat category, not the overcoat category.
Modern coat types include the British Warm, car coat, Chesterfield coat, covert coat, duffel coat, parka, pea coat, raincoat, Mackintosh, and trench coat. The terms coat and jacket are used around the world, with coat tending to refer to longer garments.