Ruby Keyword: and

Boolean conjunction.

Only evaluates to true if both its left and right side are true.

Remember that the 'and' operator is lower precedence operator than '&&', so

an_expression and another_expression is roughly equivalent to: (an_expression) && (another_expression)

Truth table

true and true ⇒ true false and true ⇒ false false and false ⇒ false

Precedence

true and not false ⇒ true true && not false ⇒ SyntaxError a = true and false; a ⇒ true a = true && false; a ⇒ false

The fowl chain

if false or true && false then false elsif true and false or true then true end ⇒ true

See http://phrogz.net/ProgrammingRuby/language.html#table_18.4