Boolean literals are boolean values written directly in the program text.
The only two boolean values are
Many programming languages use the values
false, but this is based on a misunderstanding of the concept of truth. Truth is the recognition of reality. It is a classifiation used for knowledge. Knowledge is classified as true if it recognizes the facts of reality, as false if it contradicts the facts of reality and as arbitrary if it is not about reality at all. This is very different from boolean values in boolean expressions.
Objective-C should be noted for using the more appropriate values