[summary: A boolean is a mathematical quantity that can only take on one of two values: "[-true]" or "[-false]". Booleans are to Logic what integers are to [-arithmetic].]

In formal Logic, a boolean variable is a [-variable] that can take on one of only two possible values: "[-true]" or "[-false]". Propositions can then be said to [-evaluation evaluate] to one of these two values, in the same way that ordinary [algebra algebraic] expressions evaluate to a Number.

Also as in algebraic expressions, boolean values can be manipulated using certain operators such as [and*operator $~$\land$~$ (and)], [or*operator $~$\lor$~$ (or)], [negation*operator $~$\neg$~$ ([negation)], and [implication*operator $~$\rightarrow$~$ (implication)]. This field is called, surprisingly, [-boolean_algebra].

Because booleans can only express absolute truth or falsity, when working with measures of uncertainty you must use other representations, such as Probability.