Because the + operator favors string concatenation. When one operand is a string, the other is coerced to a string, so 1 becomes '1' and the result is '12'.

== coerces operands to a common type before comparing, so '0' == 0 is true. === checks both type and value without coercion, so '0' === 0 is false. Always prefer ===.

Dynamically and weakly typed. Types are checked at runtime, not compile time, and the engine coerces values automatically when types mismatch.