Because by saying "CHEESE" we show those pearly whites. Maybe not a true smile, but close enough for most pictures.

It's easier to smile when you're saying a word like "cheese" that makes you bear your teeth. :-)

Because it makes a smiley face, but there is another word that makes a better face but is very rude . Photographers used to tell us to say it quietly

"Cheese" contains the phoneme /i/, a long vowel which makes our lips stretch to make a smile. I am unsure why "cheese" was chosen or where it originated to be the universal smiley word.

Photographers across the country attempted to induce a laugh from their subjects. Many methods were tried, but none found as much success as the original approach. Sadly, even eating refried beans by the gallon cannot induce flatulence on demand, so photographers resorted to mentioning the original story. For several years, camera subjects would be told “did you hear the one about the photographer that cut the cheese?” just prior to the snapping of a shot, which almost never failed to get a laugh. Over the years, photographers began to shorten the reference, saying only “the one about cutting the cheese,” and still later merely “cut the cheese.” Eventually, they arrived at the short “cheese” of today, which conveniently causes the aforementioned smile-like mouth position, a remarkable serendipity of function following form. Ever since, photographers have implored their subjects to say the word “cheese,” in a now-forgotten reference to wind broken nearly a century ago. And so, the fermented dairy product we know as cheese became inexorably linked to the taking of photographs, as it remains to this day. http://www.lukeswartz.com/writing/cheese.html

I believe there was a photographer back in 1943 who was disatisfied with his hamburger while taking a picture. He asked what would make it better and right when he took the picture the picturee said how about some "cheeeeeese"

Yes, there are a few words that you can't help but show your teeth when saying, and cheese is one of them.

Those answers are all wrong. Here is the correct answer. The English say "Cheers" when they pose for photos, I suppose the American "cheese" comes from that. We just got it wrong, that's all. The English say "cheers" with the English accent, it sounds like "cheese." That's all. We use the wrong word. We should say cheers, but Americans don't often say cheers like the English do, and if we say cheers with an American accent it doesn't make you smile. It makes your lips pucker with "r" but the English don't pronounce the "r" so they smile.

The dairy union worked with the camera lobby for a very successful cross-promotion between the two industries.

(idiomatic) Used imperatively to elicit a smile from someone for a photograph by their saying "cheese" (the vowel of which, when pronounced as is usual in English, forces a somewhat smile-shaped mouth). Usage notes The term seems to have led to the word "cheese" becoming a slang synonym for "smile". http://en.wiktionary.org/wiki/say_cheese Say "cheese" is an instruction used by photographers who are having difficulty getting their subject to smile. By saying "cheese", most people form their mouths into what appears to be a smile-like shape. Additionally, the absurdity of saying "cheese" for no apparent reason can incite glee in some persons. As this practice became ingrained into modern society, it has taken on the simple role of a final warning before a photograph is taken. Often subjects will simply use the phrase "say cheese" as a cue to enter their final pose and to smile, neglecting to actually say "cheese". Over the years, many other words have been used in place of cheese. For comedic effect, a photographer might say "Say ______" filling the blank with a word relevant to the event or action he is photographing. (Ex. "Say wipe out" during a seaside photograph) Other times a person will fill the blank with an absurdist or seemingly entirely random word of their choice. Perhaps due to strong Western influence, especially in the realm of photography, and perhaps due to increased numbers of Western visitors after photographic equipment became widely available, the phrase "Say Cheese" has also entered into the Japanese language. However, the word "say" is almost always dropped from the phrase, resulting in the phrase simply being "Cheese." This is usually pronounced in Japanese (and written in katakana) as "chiizu". Other languages have adopted this method, albeit with different words that sound similar to cheese to get the desired effect of shaping the mouth to form a smile. For example, in China, the word used is xxxx, meaning 'eggplant'. In Korea, one would say "kimchi." In France, the word "Ouistiti", meaning marmoset, is often used. In most Latin American countries, the phrase used is "Diga whiskey" ("Say whiskey"). http://en.wikipedia.org/wiki/Say_cheese Many methods were tried, but none found as much success as the original approach. Sadly, even eating refried beans by the gallon cannot induce flatulence on demand, so photographers resorted to mentioning the original story. For several years, camera subjects would be told “did you hear the one about the photographer that cut the cheese?” just prior to the snapping of a shot, which almost never failed to get a laugh. Over the years, photographers began to shorten the reference, saying only “the one about cutting the cheese,” and still later merely “cut the cheese.” Eventually, they arrived at the short “cheese” of today, which conveniently causes the aforementioned smile-like mouth position, a remarkable serendipity of function following form. (more.........) http://www.lukeswartz.com/writing/cheese.html

it is just simply becos our mouth will lift upward when saying cheese

"Fromage" makes for awkward photos.

I think someone cut the cheese right before an early the photograph was taken, that made everyone smile, and photographers adopted that as a way to get people to smile.