StudlyCaps is a form of text notation in which the capitalization of letters varies by some pattern, or arbitrarily, usually also omitting spaces between words and often omitting some letters. Such patterns are identified by many users, ambiguously, as CamelCase. The typical alternative is to replace_spaces_with_underscores (as in Snake_case).
According to the Jargon File, "ThE oRigiN and SigNificaNce of thIs pRacTicE iS oBscuRe." Arbitrary variation found popularity among adolescent users during the BBS and early WWW eras of online culture, as if in parody of the marginally less idiosyncratic capitalization found in common trade and service marks of the time. Programming style guides, meanwhile, began to codify common StudlyCaps patterns for computer programmer populations, who are constrained by rules on the placement of whitespace that are incompatible with natural-language usage.
Unlike the use of all-lowercase letters, which suggests efficiency as a motivation, StudlyCaps requires additional effort to type (and read), either holding and releasing the shift key with one hand while hunting-and-pecking, or intermittently pressing one shift key or the other while touch typing. The iNiQUiTY BBS software based on Renegade had a feature to support two variants of this automatically. Either all vowels would be uppercase or all vowels would be lowercase, with the non-vowels as the other case.
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Numerous authorities have published mutually incompatible specifications for which letters must, may, or must not be capitalized or omitted for a StudlyCaps expression to qualify, additionally, as (presumed non-parodic) CamelCase. Continued use of StudlyCaps is reinforced by requirements in most computer languages that even multi-word names must include no spaces, coupled with increasing use of such multi-word names.
See also 
- "studlycaps". The Jargon File, version 4.4.7. 29 Dec. 2003. Retrieved 12 Jun. 2009.