Source for inspiration: https://riptutorial.com/common-lisp/example/11082/conditional-constructs

If

;;(if (predicate)
;;    (do this if true...)
;;  (do this if false...))

(if (TRUE)
    (print "This is true")
  (print "This is false")) ;; will always print "This is true"

;; use progn for multiline statements
(if (TRUE)
    (progn
      (print "Test1")
      (print "Test2"))
  (print "No tests"))
;; this prints Test 1 then Test 2 and returns Test2

When

;; short hand for if with only one path
(when (> 3 4)
  (print "I got here")
  "Three is bigger than four")
;; prints "I got here" and returns "Three is bigger than four"

Unless

;; The inverse of when, runs body only when condition is false
(unless (> 3 4)
  "Three is not bigger than four!")
;; Returns "Three is not bigger than four!"

Cond

;; run multiple conditions in one body
(cond ((> 3 4) "Three is bigger than four!")
      ((> 3 3) "Three is bigger than three!")
      ((> 3 2) "Three is bigger than two!"))
;; Returns "Three is bigger than two!"