performs a short-circuiting and
Evaluates the forms from left to right. As soon as one evaluates to a falsey value, will return that value. Otherwise it will proceed to evaluating the next form.
(and (+ 1 2 3) false "not returned")
Will return #f (false), never evaluating “not returned”, whereas:
(and (+ 1 2 3) true "returned")
Will return the string “returned”.