Mercery (from French mercerie, meaning "haberdashery" or goods, or "haberdashery"—a shop trading in textiles and notions) initially referred to silk, linen and fustian textiles among various other piece goods imported to England in the 12th century. Eventually, the term evolved to refer to a merchant or trader of textile goods, especially imported textile goods, particularly in England. A merchant would be known as a mercer, and the profession as mercery.

The occupation of mercery has a rich and complex history dating back over 1,000 years in what is now the United Kingdom. London was the major trade centre in England for silk during the Middle Ages, and the trade enjoyed a special position in the economy amongst the wealthy.

A typical mercery business was family-run, consisting of a mercer, wife, their family, servants, and apprentices. The husband would be tasked with the marketing and sale of the business's wares to the public in places such as a small storefront, at markets, and at public fairs. The wife would operate mainly in the workshop, using her skills to buy the business's stock and make various silk cloths and piece goods; she would also be in charge of the workshop alongside her husband, and would often be expected to train the apprentices and the family's children to contribute to the household income.

The term mercer in reference to a cloth merchant (from the French mercier, originally referring to a person importing fabric goods from the Eastern world) is now largely obsolete.

Mercers were merchants or traders who dealt in cloth, typically fine cloth that was not produced locally. Inventories of mercers in small towns, however, suggest that many were shopkeepers who dealt in various dry commodities other than cloth. Related occupations include haberdasher, draper and cloth merchant, while clothier historically referred to someone who manufactured cloth, often under the domestic system.

In the 21st century, the word mercer is primarily used in connection with the Worshipful Company of Mercers, the first in precedence of the twelve Great Livery Companies of the City of London.

In earliest use, the term mercery was amorphous in nature, and described the sale of a wide range of goods, from small items like needles and thread, to expensive materials such as silk or brocade. The term can be dated to the early 11th century. The first reference to mercery was in use for foreign merchants from modern-day Germany, France and the Netherlands, who were well-placed geographically to transport luxuries from the East and their own manufactured goods into England.

Only in the 12th century did the term mercery as an occupation become distinctly separate from the general merchant, who might only deal with linen. Mercery became associated with silk, linen, and various piece goods, especially high-quality products such as dress accessories, small luxuries and beddings—different from the simple everyday wear of the masses, which would typically be made of either linen or wool. The trade of silk and expensive clothes set apart the profession of a mercer from that of a general merchant, as was formally outlined under trading regulations in London; as a major trading hub of the time, the number of mercers was sufficiently extensive as to allow certain goods to be clearly defined as mercery, in laws specifically aimed to control prices and protect local mercers through supply and demand.