Since the same sort of pan is universal in India and Southeast Asia, where it is known as a Kuali in several languages, I strongly suspect borrowing [of the word] (probably from India via Central Asia)--kuo must have evolved from some word close to Kuali.The first possible depictions of woks in China appeared in the Han dynasty (c. 202 BCE - 220 CE).

[7] Metal woks only started to appear in China in the Ming dynasty (1368 - 1644), where it was first used for stir frying (an original Han Chinese innovation).

Smaller woks are typically used for quick cooking techniques at high heat such as stir frying (Chinese: 炒; pinyin: chǎo).

Large woks over a meter wide are mainly used by restaurants or community kitchens for cooking rice or soup, or for boiling water.

[2] Although the latter was the most common type used in the past, cooks tend to be divided on whether carbon steel or cast iron woks are superior.

[2] Carbon steel woks vary widely in price, style, and quality, which is based on ply and forming technique.

[2] Cast iron woks form a more stable carbonized layer of seasoning which makes it less prone to food sticking on the pan.

[13][14] Woks are also now being introduced with clad or five-layer construction, which sandwich a thick layer of aluminum or copper between two sheets of stainless steel.

Cooking with the tossing action in loop-handled woks requires a large amount of hand, arm and wrist strength.

[2] The classic stick handle is made of hollow hammered steel, but other materials may be used, including wood or plastic-covered hand grips.

Before the introduction of Western cookware, it was often used for all cooking techniques including:[2][15] "Wok hei" (simplified Chinese: 镬气; traditional Chinese: 鑊氣; pinyin: huò qì; Jyutping: wok6 hei3) literally, the "breath of the wok", is the distinct charred, smoky flavor resulting from stir-frying foods over an open flame in Cantonese cuisine.

[2][17] It is particularly important for Cantonese dishes requiring high heat for fragrance such as char kuay teow and beef chao fen.

Consequently, many chefs (especially those with less-than-ideal cookers) may cook in small batches to overcome this problem so that the wok is still as hot as it can be, and to avoid "stewing" the food, instead.

In practical terms, the flavor imparted by chemical compounds results from caramelization, Maillard reactions, and the partial combustion of oil that come from charring and searing of the food at very high heat in excess of 200 °C (392 °F).

[citation needed] In Hong Kong, wok hei is traditionally street food, cooked in open-air dai pai dongs ("big license stalls") over a very hot kerosene flame.

[18] In Indonesia, a wok-like pan is known as a penggorengan or wajan (also spelled wadjang, from Javanese language, from the root word waja meaning "steel").

[citation needed] Pit stoves originally burned wood or coal but are now more typically heated by natural gas with the burner recessed below the stovetop.

Professional chefs in Chinese restaurants often use pit stoves since they have the heating power to give food an alluring wok hei.

Although not as ideal as "pit stoves", these allow woks to be used in a manner more suitable for their design and are good enough for most tasks required in home cooking.

In recent years, some consumer indoor stoves using natural gas or propane have begun offering higher-BTU burners.

A few manufacturers of such stoves, notably Kenmore Appliances and Viking Range Corp. now include a specially designed high-output bridge-type wok burner as part of their standard or optional equipment, though even high-heat models are limited to a maximum of around 27,000 BTU (7.9 kW).

[citation needed] Woks, round or flat bottomed, do not generally work well for stir-frying or other quick cooking methods when used on an electric cooker.

Many Chinese cooks use Western style cast-iron pans for stir-frying on electric stoves, since they hold enough heat for the required sustained high temperatures.

The large sloped sides also make it easier for chefs to employ the tossing cooking technique on solid and thick liquid food, with less spillage and a greater margin of safety.

The curved sides also allow a person to cook without having to "chase the food around the pan", since bite-sized or finely chopped stir-fry ingredients usually tumble back to the center of the wok when agitated.

[2] The curve also provides a larger usable cooking surface versus Western-style pots and pans, which typically have vertical edges.

This allows large pieces of food seared at the bottom of the wok to be pushed up the gently sloped sides to continue cooking at a slower rate.

[2] As such, large food items can be shallow fried, while finely chopped garlic, chili peppers, scallions, and ginger can be essentially deep-fried in both cases with very small amounts of cooking oil.