What does ISO stand for in cameras?

"ISO" is a word that represents the International Standards Organization, or as it is more commonly known, the International Organization for Standardization. This organization is based in Switzerland and they set a lot of international standards, including the measurement system for film sensitivity (which translates to digital photography).

In photography, the ISO is pronounced "EYE-so," not "eye-es-oh," however it does not have anything to do with the Greek "isos," as others have claimed. Here is the entry in the World English Dictionary:

ISO (aɪsaʊ)
-n
International Organization for Standardization

[Greek isos equal; often wrongly thought to be an abbreviation for International Standards Organization ]