Text sometimes exhibits case sensitivity; that is, words can differ in meaning based on differing use of uppercase and lowercase letters. Words with capital letters don't always ...
http://en.wikipedia.org/wiki/Case_sensitivity

text) case sensitivity - Whether a text matching operation distinguishes upper-case (capital) letters from lower case (is "case sensitive") or not ("case insensitive").
http://encyclopedia2.thefreedictionary.com/case+sensitivity

Case Sensitivity Is What Prevents You Logging On To Your Computer When CapsLock Is Turned On.
http://uncyclopedia.wikia.com/wiki/Case_sensitivity

To avoid confusion and guarantee cross-language interoperation, follow these rules regarding the use of case sensitivity: Do not use names that require case sensitivity.
http://msdn.microsoft.com/en-us/library/04xykw57.aspx

Case sensitivity in MediaWiki is both a blessing and a curse. Whether or not the trade off is worth it, is beside the point. Some times case matters, and preserving case allows ...
http://meta.wikimedia.org/wiki/Case_sensitivity