Image by Nigel Swales on Flickr

Software programming does neat things with language, in this case, mixing capital letters.

Which do you think is easier to read, arrsomebigcollectionofdata or arrSomeBigCollectionOfData? If you read software code long enough, you will notice uppercase and lowercase letters are everywhere. What gives?

It’s not a secret code, exactly, and there’s no mysterious list of when to use capital letters and when not. Instead, it’s an example of how software programmers take a technical problem — in this case, how to make code readable — and find a fun way to describe the solution.

The use of capitals and lowercase letters is called CamelCase with the capital letters as the humps in the camel. It’s also been called BumpyCaps and HumpBack and a few other words. The most boring is the technical term, medial capitals. For some reason, CamelCase has stuck despite many cases where there are far more capital letters used than humps in a camel.

There’s also lower CamelCase which begins with a lowercase letter and upper CamelCase which begins with a capital letter.

The rules for how to use CamelCase are set by whoever decides the overall programming standards for a project. Sometimes those standards are defined by the creators of the language used. But mostly the rules for CamelCase tend to be lower CamelCase for variable names and upper CamelCase for functions, methods, and other blocks of code.

In some cases, lower CamelCase also is used to indicate functions and methods that can be used anywhere in the code (public) and upper CamelCase for code blocks that can only be used within another code block (private).

Regardless of the rules, using lower and uppercase letters helps programmers understand the role a name has within their software code.

Learn More


Naming Conventions (Programming)

CamelCase Generator

What is the point of the lower camel case variable casing convention (thisVariable, for example)?

Snake Case

Tall Man Lettering

Title Case


  • Tim Slavin

    Tim is an award-winning writer and technologist who enjoys teaching tech to non-technical people. He has many years experience with web sites and applications in business, technical, and creative roles. He and his wife have two kids, now teenagers, who are mad about video games.

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