# Boolean (true or false)

A boolean is a true or false value, and you type them just like that, `true` and `false`.

Often in programming, we need to ask a true or false question, like:

• "Is this class in the current semester?"
• "Is this person's birthday today?"

When we ask those questions, we get a boolean value returned.

## Functions that return boolean values

The functions `true?` and `false?` are used to test if a value is either true or false.

The `=` function is used to compare two values. If they are equal, then `true` is returned, if not then its `false`

Other functions (also known as predicates) also return `true` or `false`

• `odd?` and `even?` will tell you if a number is odd or even

### Evaluate the Boolean values and functions that return boolean values in the REPL

Type some expressions to test out the truthiness of things.

Look at the truthiness reference guide for more examples

``````;; (true? (= 1 1))
(false? (= 7 (+ 3 3)))
``````

### Hint

There is another value `nil`, which behaves like a boolean in terms of truthiness.

But, `nil` means no value at all and not a boolean

Boolean values are often used in functions that evaluate a condition, such as `for` or `cond`.

Reference: Truthiness