A boolean value describe a value that is either true or false. Boolean values can be used with boolean operators only and are evaluated to boolean values again.
However, boolean values are not necessarily required in lua. Following codes will result in the same output:
iftruethenprint "one" endiffalsethenprint "two" endiffalseortruethenprint "three" endifnotfalseandtruethenprint "four" end
if 0 thenprint "one" endifnilthenprint "two" endifnilor "ok" thenprint "three" endifnotniland 1 thenprint "four" end
Both sources will print
Any value in Lua that is not false or not nil will be evaluated as false, while all other values will be evaluated as true (even the number 0 will be evaluated as true, unlike as in some other programming languages).