Basic Examples (1) 

Produce a String telling whether a number is even or odd:

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Scope (3) 

The condition, as well as f and o, can be the name of a function:

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Or they can be pure functions, or a mixture of both names of functions and pure functions:

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Symbolic expressions are allowed. This example applies f to the expression if it has two items; otherwise, it applies g:

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Applications (1) 

If a word has conjugations or forms other than itself, return them; otherwise, return Missing[]:

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Properties and Relations (1) 

If the condition evaluates to something other than True or False, the "otherwise" function (the last argument) is evaluated. Here, the condition returns an image of a hot dog:

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Possible Issues (2) 

All arguments to this function except the first are required to be functions. Therefore, the following will not work:

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Rather, make the arguments into pure functions like so:

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