The whole, ground, cracked, or bruised mustard seeds are mixed with water, vinegar, lemon juice, wine, or other liquids, salt, and often other flavorings and spices, to create a paste or sauce ranging in color from bright yellow to dark brown.

Mustard is commonly paired with meats, vegetables and cheeses, especially as a condiment for sandwiches, hamburgers, and hot dogs.

The first element is ultimately from Latin mustum ("must", unfermented grape juice)—the condiment was originally prepared by making the ground seeds into a paste with must or verjuice.

[3] Evidence of mustard in the archaeological record is scarce since species in the Brassicaceae family do not accumulate silica and therefore do not produce phytoliths.

[4] The earliest evidence of humans using mustard plants as food dates to the Pre-Pottery Neolithic site of Jerf el Ahmar in Syria.

[7] The Romans mixed unfermented grape juice (the must) with ground mustard seeds (called sinapis) to make ‘burning must’, mustum ardens.

A recipe for mustard appears in De re coquinaria, the anonymously compiled Roman cookery book from the late fourth or early fifth century: the recipe calls for a mixture of ground mustard, pepper, caraway, lovage, grilled coriander seeds, dill, celery, thyme, oregano, onion, honey, vinegar, fish sauce and oil and was intended as a glaze for spit-roasted boar.

[9] The early use of mustard as a condiment in England is attested from the year 1390 in the book The Forme of Cury, which was written by King Richard II's master cooks.

[13] The town of Tewkesbury was well known for its high-quality mustard balls, originally made with ground mustard mixed with horseradish and dried for storage,[14] which were then exported to London and other parts of the country, and are even mentioned in William Shakespeare's play King Henry the Fourth, Part II.

The basic taste and "heat" of the mustard are determined largely by seed type, preparation, and ingredients.

Prepared mustard is sold in glass jars, plastic bottles, or metal squeeze tubes.

[30] Because of its antibacterial properties and acidity, mustard does not require refrigeration for safety; it will not grow mold, mildew, or harmful bacteria.

Some types of prepared mustard stored for a long time may separate, which can be corrected by stirring or shaking.

[32] When whole mustard seeds are crushed and mixed with a liquid, an enzyme is activated that releases pungent sulfurous compounds, but they quickly evaporate.

[33] However prepared mustard loses its pungency over time; the loss can be slowed by keeping a sealed container (opaque or in the dark) in a cool place or refrigerator.

Locations renowned for their mustard include Dijon and Meaux in France; Norwich and (historically) Tewkesbury in England; and Düsseldorf, Bautzen, and Bavaria in Germany.

A variety popular in Louisiana is called Creole mustard, which is much coarser than most spicy brown types.

It is made with a combination of yellow and brown seeds and is stronger than many other mustards as it has a low acid content.

A woman based in Durham by the name of Mrs Clements was the first person to sell English mustard in a prepared format in 1720.

[11] Large chunks of fruit preserved in a sweet, hot mustard syrup were served with meat and game, and were said to be a favorite of the Dukes of Milan.

In various areas of Italy, the term mostarda refers to sweet condiments made with fruit, vegetables, and mosto, grape juice that gets simmered until syrupy.

Moutarde douce is a sweetened mustard usually containing other herbs found in France, though less common than Dijon style.

Sweet mustard from Tecuci, Romania, is a variety very popular in Southeastern Europe and is suitable for grilled meats such as mititei.

In the European Union labeling the presence of mustard in packaged food is compulsory, either as an ingredient or even as unintended contamination in trace amounts.