What is CamelCase?

CamelCase is a method of writing that joins compound words without leaving a space between them. Both words are capitalized, which means there is a capital letter at the beginning and in the middle of the combined words. Also known as camel-case or medial capitals, this method is most often used when denoting chemical formulas but may also be used in proper names, in computer programming languages and in advertising. It is called camelcase because the word resembles a two-humped camel when written out.

The camelcase method of writing chemical formulas was invented by Berzelius in 1813. Berzelius, who was a Swedish chemist, felt it was easier to have chemical formulas written this way to illustrate compounds. For example, the periodic table symbol for sodium is Na and the symbol for chloride is Cl. When mixed as the compound sodium chloride, the symbol is written as NaCl.

Proper names are one way camelcase is used when writing. Seen more in last names than given names, camelcase proper names are very common in Scotland and Ireland but are also found in other countries around the world. Popular examples include DuPont, McCloud, MacLean, VanDyke, and DiCaprio.

Computer programmers have used medial capitals since the 1970s as a way to document common multi-word descriptions used in their computer code. In order to make the descriptions universally understood by various computer programming languages such as COBOL, Modula, PARC, and PostScript, programmers adopted a similar naming convention. For example, instead of writing End of File, End_of_File, or End-of-File, programmers simply write EndofFile, which is much quicker and does not conflict with other programming rules for special characters.

Advertising is another area where camelcase spelling methods are popular. When marketing brands of products or companies, many owners choose camelcase spellings. This is especially true in the electronics industry, since users were already comfortable with medial capitals due to its use in computer programming languages. Examples include iPod, TiVo, eBay, BlackBerry, MySpace, YouTube, and PayPal.

Some early adopters of the medial capitals were McDonald's, BellSouth, MasterCard, TriStar Pictures, and ThinkPad. Whether a company name or product name, marketers felt the use of medial capitals made it easier for consumers to remember their products. Some companies have even changed their names to reflect camelcase from other spellings. FedEx used to be Federal Express, PetSmart used to be PETsMART, and RadioShack used to be Radio Shack.