A doily is an ornamental mat, originally the name of a fabric made by Doiley, a 17th-century London

London

London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

 draper

Draper

Draper is the now largely obsolete term for a wholesaler, or especially retailer, of cloth, mainly for clothing, or one who works in a draper's shop. A draper may additionally operate as a cloth merchant or a haberdasher. The drapers were an important trade guild...

. Doily earlier meant "genteel, affordable woolens", evidently from the same source.

They are crochet

Crochet

Crochet is a process of creating fabric from yarn, thread, or other material strands using a crochet hook. The word is derived from the French word "crochet", meaning hook. Hooks can be made of materials such as metals, woods or plastic and are commercially manufactured as well as produced by...

ed and sometimes knitted

Knitting

Knitting is a method by which thread or yarn may be turned into cloth or other fine crafts. Knitted fabric consists of consecutive rows of loops, called stitches. As each row progresses, a new loop is pulled through an existing loop. The active stitches are held on a needle until another loop can...

 out of cotton

Cotton

Cotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium. The fiber is almost pure cellulose. The botanical purpose of cotton fiber is to aid in seed dispersal....

 or linen

Linen

Linen is a textile made from the fibers of the flax plant, Linum usitatissimum. Linen is labor-intensive to manufacture, but when it is made into garments, it is valued for its exceptional coolness and freshness in hot weather....

 thread. Openwork

Cutwork

Cutwork or cut work is a needlework technique in which portions of a textile are cut away and the resulting "hole" is reinforced and filled with embroidery or needle lace.Cutwork is a related to drawn thread work...

 allows the surface of the underlying object to show through. In addition to their decorative function doilies have the practical role of protecting fine-wood furniture from the scratches caused by crockery or decorative objects.

Many patterns for crocheting or knitting doilies were published by thread manufacturers in the first part of the 20th century.