Case sensitivity

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For a discussion of case-sensitivity in Wikipedia page titles, see Help:Page name and Wikipedia:Naming conventions (capitalization).

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 have the same meaning when written with lowercase letters. For example, Bill is the first name of former U.S. president Bill Clinton, who could sign a bill (which is a proposed law that was approved by Congress). And a Polish person can use polish to clean something.

When a computer program compares two words to decide whether they are the same, it might or might not apply case sensitivity, depending upon the programmer’s intent.

Case sensitivity is relevant to:

usernames
passwords
filenames
tags
commands
variable names
website addresses
searching for a text string within electronic text

Some computer languages are case-sensitive (Java, C++, C([1]), Ruby([2]) and XML), whereas others are case-insensitive (i.e., not case-sensitive), for example, most BASICs (an exception being BBC BASIC), SQL and Pascal. There are also languages, such as Haskell and Prolog, in which the capitalization of an identifier encodes information about its semantics.

Often, computer passwords are case-sensitive and computer user names are not, which can be confusing for the inexperienced user. Passwords are often made case-sensitive to make them harder to guess, where