Thyme is the herb (dried aerial parts) of certain members of the genus Thymus of aromatic perennial evergreen herbs in the mint family Lamiaceae. Thymes are related to the oregano genus Origanum, with both plants being primarily native to the Mediterranean region. Thyme has culinary, medicinal, and ornamental uses, and the species most commonly cultivated and used for culinary purposes is Thymus vulgaris.

History

Thyme is native to the Mediterranean region. Wild thyme grows in the Levant. The ancient Egyptians used thyme for embalming. The ancient Greeks used it in their baths and burned it as incense in their temples, believing it to be a source of courage. The spread of thyme throughout Europe was thought to be due to the Romans, who used it to clean their rooms and to "give an aromatic flavor to cheeses and liqueurs." In the European Middle Ages, the herb was placed under pillows to aid sleep and prevent nightmares. During this period, women also often gave gifts to knights and warriors that included thyme leaves, as they were believed to give courage to the bearer. Thyme was also used as incense and placed in coffins during funerals, as it was believed to ensure passage to the afterlife. 

Cultivation
Thyme grows best in a warm, sunny location with well-drained soil. It is generally planted in spring and then grown as a perennial. It can be propagated by seed, cuttings, or by dividing rooted parts of the plant. It tolerates drought well. The plant can be frozen hard and is found growing wild in mountainous highlands. It can be pruned after flowering to prevent woody growth.

Fragrance ingredients
Gas chromatographic analysis reveals that the most abundant volatile component of thyme leaves is thymol 8.55 mg/g. Other components are carvacrol, linalool, α-terpineol, and 1,8-cineole. Several are also found in basil. Some exhibit antioxidant properties.

In some Levantine countries and Assyria, the spice za'atar (Arabic for thyme and marjoram) contains many of the essential oils found in thyme. Thyme is a common ingredient in bouquet garni, and herbs de Provence.

Thyme is sold both fresh and dried. The fresh form is tastier, but also less convenient. The shelf life is rarely more than a week. However, the fresh form can last for many months if carefully frozen.

Depending on how it is used in a dish, the entire branch can be used (e.g. in a bouquet garni) or remove the leaves and discard the stems. Usually, when a recipe specifies a "bunch" or "sprig," it means the whole form. When it specifies tablespoons, it means the leaves. It is perfectly acceptable to substitute dried for whole thyme.
Thyme retains its flavor when dried better than many other herbs.

Antimicrobial properties

Thyme essential oil (Thymus vulgaris):
Thyme oil, the essential oil of common thyme (Thymus vulgaris), contains 20–54% thymol. Thyme essential oil also contains a number of additional compounds, such as p-cymene, myrcene, borneol, and linalool. Thymol, an antiseptic, is an active ingredient in various mouthwashes. Before the advent of modern antibiotics, thyme oil was used to treat wounds.