Simplified Common Lisp reference
Symbol class: Mathematics, Arithmetics, Logic and Comparisons
Symbol type: macro
andforms(zero or more) => value
Argument description:
forms forms which value is considered

AND macro computes logical "and" function. Forms evaluation starts from left. Value from the first form that decides result is returned so forms at end of argument list may not evaluated.

(and t t t nil t) => NIL
(and t t t t) => T
(and) => T
(and (progn (write "SEEN") nil) (progn (write "UNSEEN") t)) => "SEEN" NIL
(and 4 5 6) => 6
Function indexFull documentation for and (HyperSpec)