Short answers, pulled from the story.
The English word merchant comes from the Middle English marchant, derived from the Anglo-Norman marchaunt, which itself originated from the Vulgar Latin mercatant or mercatans, formed from the present participle of mercatare, meaning to trade, to traffic, or to deal in.
Merchants were broadly classified as wholesale merchants, who operated between producers and retailers and typically handled large quantities of goods without selling directly to end-users, and retail merchants, who sold merchandise directly to consumers, usually in small quantities.
The first known merchant guild formed in 1020 in Tiel, in what is now the Netherlands. The term guild itself first appears in reference to a body of merchants called the gilda mercatoria, operating out of St. Omer, France, in the 11th century.
The Phoenicians became a major Mediterranean trading power by the 9th century BCE, holding a monopoly on purple dye from the murex shell and trading wood, textiles, glass, wine, oil, and dried fruit. Around 1500 BCE they developed an alphabet that was easier to learn than Egyptian or Mesopotamian pictographic systems, and Phoenician merchants spread that script across the region as they expanded their trade networks.
Josiah Wedgewood, who lived from 1730 to 1795, used direct mail, travelling salesmen, and catalogues to reach customers. He also investigated fixed and variable production costs, recognized that higher output would lower per-unit costs, and understood that selling at lower prices would generate higher overall demand and profit.
Daniel Parker was a merchant from Watertown, Massachusetts, who escaped his debts after the Revolutionary War by boarding a ship to Europe, where his reputation had not followed him. His case illustrated how post-war merchant networks relied on personal trust and honor systems in place of hard currency, and how geographic mobility could allow dishonest merchants to reset their reputations and exploit new trading partners.