Internal capitalization

Camel case (stylized as camelCase or CamelCase; also known as camel caps or more formally as medial capitals) is the practice of writing compound words or phrases such that each word or abbreviation in the middle of the phrase begins with a capital letter, with no intervening spaces or punctuation. Common examples include "iPhone", "eBay", "FedEx", and "HarperCollins". It is also sometimes used in online usernames such as "JohnSmith", and to make multi-word domain names more legible, for example in advertisements.

As the first letter of a compound word in camel case may or may not be capitalized, there is no consensus on whether the term "camel case" implies an uppercase or lowercase initial letter. For clarity, this article calls the two alternatives upper camel case (initial upper case letter also known as Title Case) and lower camel case (initial lower case letter). Some people and organizations, notably Microsoft, use the term camel case only for lower camel case.

Camel case is distinct from title case, which is traditionally used for book titles and headlines, as the latter retains the spaces between the words. Camel case is also distinct from Tall Man lettering, which uses capitals to emphasize the differences between similar-looking words.

The name "CamelCase" is not related to the "Camel Book", the popular nickname of the book Programming Perl, which uses all-lowercase identifiers with underscores in its sample code.

The original name of the practice, used in media studies, grammars and the Oxford English Dictionary, was "medial capitals". Other names such as "InterCaps" or "CamelCase" are relatively recent and more common in computer-related communities. Other synonyms include:

StudlyCaps encompasses both styles of camel case, but includes even randomly mixed capitalization, as in MiXeD CaPitALiZaTioN (typically a stereotyped allusion to online culture).

...
Wikipedia