A potato chip or crisp is a thin slice of a potato deep fried or baked until crisp. Potato chips serve as an appetizer or snack. Commercial varieties are packaged for sale, usually in bags. The simplest chips are simply cooked and salted, but manufacturers can add a wide variety of seasonings (mostly made using herbs or spices, artificial additives or MSG). Chips are an important part of the snack food market in English-speaking countries and many other "western" nations.

There is little consistency in the English speaking world for names of fried potato slices. North American English uses chips for the above mentioned dish, crisps for the same made from batter, and French fries for the chewier dish. In European English, crisps are used for the crispy dish and chips for the chewy dish (as in "fish and chips"). In Australia, New Zealand and South Africa, both forms of potato product are simply known as chips, as are the larger "home-style" potato chips. Sometimes the distinction is made between hot chips and packet chips. Kumara (sweet potato) chips are eaten in New Zealand and Japan.

There are also regional variations too. For example, in the North of England, fried sliced potatoes are called flakies.

Origins
It is believed that the original potato chip recipe was created by Native American/African American chef George Crum, at Moon's Lake House near Saratoga Springs, New York on August 24, 1853. He was fed up with a customer — by some accounts Cornelius Vanderbilt (although this has been disproved) — who continued to send his fried potatoes back, because they were too thick and soggy. Crum decided to slice the potatoes so thin that they couldn't be eaten with a fork. Against Crum's expectation, the guest was ecstatic about the new chips. They became a regular item on the lodge's menu under the name "Saratoga Chips". They soon became popular throughout New England. Eventually, potato chips spread beyond chef-cooked restaurant fare and began to be mass produced for home consumption; Dayton, Ohio-based Mike-sell's Potato Chip Company, founded in 1910, calls itself the "oldest potato chip company in the United States."

Before the airtight sealed bag was developed, chips were stored in barrels or tins. The chips at the bottom were often stale and damp. Then Laura Scudder invented the bag by ironing together two pieces of wax paper, thereby creating an airtight seal and keeping the chips fresh until opened. Today, chips are packaged in plastic bags, with nitrogen gas blown in prior to sealing to lengthen shelf life, and provide protection against crushing.

Economy
In 2002, the world wide sales volume of potato chips amounted to more than thirty billion dollars.

Seasoned chips
An old advertisement for Smith's Potato CrispsThe potato chip remained unseasoned until an innovation by Joe "Spud" Murphy (1923 – 2001), the owner of an Irish crisp company called Tayto, who developed a technology to add seasoning in the 1950s. Though he had a small company, consisting almost entirely of his immediate family who prepared the crisps, the owner had long proved himself an innovator. After some trial and error, he produced the world's first seasoned crisps, "Cheese and Onion" and "Salt 'n' Vinegar".

Chips seasoned with salt had been sold previously, but the salt was supplied in a sealed packet inside the bag, to be added when required. A variation on this is still available in the UK, "Smith's Salt'n'Shake" comes with a small blue bag of salt.

The innovation became an overnight sensation in the food industry, with the heads of some of the biggest potato chip companies in the United States heading to the small Tayto company to examine the product and to negotiate the rights to use the new technology. When eventually the Tayto company was sold, it made the owner and the small family group who had changed the face of potato chip manufacture very wealthy. Companies worldwide sought to buy the rights to Tayto's technique.

The Tayto innovation changed the whole nature of the potato chip. Later chip manufacturers added natural and artificial seasonings to potato chips, with varying degrees of success. A product that had had a large appeal to a limited market on the basis of one seasoning now had a degree of market penetration through vast numbers of seasonings. In the US, the most popular forms of seasoned potato chips include "sour cream and onion," "barbecue," "ranch," and cheese-seasoned chips. Various other seasonings of chips are sold in different locales, including the original "salt and vinegar," produced by Tayto, which remains by far Ireland's biggest manufacturer of crisps.

Similar foods
The regular shape of "Pringles" and similar products betrays their non-traditional manufacturing method, involving reconstituted potatoAnother type of potato chip, notably the Pringles and Lay's Stax brands, is made by extruding or pressing a dough made from ground potatoes into the familiar potato chip shape before frying. This makes chips that are very uniform in size and shape, which allows them to be stacked and packaged in rigid tubes. In America, the official term for Pringles is "crisps", but they are rarely referred to as such. Conversely Pringles may be termed "potato chips" in Europe, to distinguish them from traditional "crisps".

Some companies have also marketed baked potato chips as an alternative with lower fat content. Additionally, some varieties of fat-free chips have been made using artificial, and indigestible, fat substitutes. These became well-known in the media when an ingredient many contained, Olestra, was linked in some individuals to abdominal discomfort and loose stools.

The success of crisp fried potato chips also gave birth to fried corn chips, with such brands as Fritos, CC's and Doritos dominating the market. "Swamp chips" are similarly made from a variety of root vegetables such as parsnips, rutabagas and carrots. Japanese-style variants include extruded chips, like products made from rice or cassava.

There are lots of other products which might be called "crisps" in Britain, but would not be classed a "potato chips" because they aren't made with potato and/or aren't chipped (for example, Wotsits).

In recipes
In American cuisine, a whole class of recipes exists that use crushed potato chips, often as one would use seasoned bread crumbs. Recipes include those for cookies, pies, breadings for meatloaves and hamburgers, crumb toppings for casseroles, and in sauces or dips, among others.

A cheap recipe is the "Potato Chip Sandwich" made from a base of two slices of white sandwich bread generously spread with mayonnaise. As many potato chips as possible are heaped on one of the slices, then the second slice is placed on top and pushed down hard until all the potato chips are crushed. "Crisp sandwiches" are also popular in the UK – a student favourite sees them made with Vitalite spread. Potato chips, particularly salt and vinegar flavor, are also a possible addition to tuna salad sandwiches. The chips are layered on top of the tuna as an additional filling. Everything here described can be done also with either Doritos or Cheetos or a combination of all the three for maximum flavor experience.

In New Zealand, potato chips are added to bread with thinly spread marmite to make a "Marmite And Chip Sandwich".

Not strictly a recipe, but another method of preparing crisps is to keep the crisps in the refrigerator, prior to serving. Commonly called ‘cold crisps’, they have a mixed level of acceptance, with some finding them abhorrent, and others seeing ‘cold crisps’ as the correct method of preparation. A common fault in vending machines often results in ‘cold crisps’ being issued, even if crisps at room temperature were desired.