stock and trade

Noun

stock-in-trade (usually uncountable, plural stocks in trade)

1. (usually) Merchandise and other necessary supplies kept on hand in order to conduct business.
   • The stock-in-trade of this old gentleman comprised chronometers, barometers, telescopes, compasses, charts, maps, sextants, quadrants, and specimens of every kind of instrument used in the working of a ship's course, or the keeping of a ship's reckoning, or the prosecuting of a ship's discoveries.1846 October 1 – 1848 April 1, Charles Dickens, “chapter 4”, in Dombey and Son, London: Bradbury and Evans, […], published 1848, →OCLC
2. (usually) A technique, skill or ability habitually used by a person, group of persons, or an organization, often in the course of their business.
   • Ideas are the chief stock-in-trade of newspaper writers and generally they are the scarcest stock in market, but they do come occasionally1890, Nellie Bly, Around the World in Seventy-Two Days, chapter 1