I disagree with what the previous article states: There are languages such as Prolog where = doesn't mean assignment. In logic, = means equality, often modulo some theory. In Prolog, = means (syntactic) unification, which is distinguished from identity only by the different quantification of variables.

I would like to emphasize the distinction that smadge made, since distinguishing between universal and existential quantification is important to properly discuss different meanings and usage modes of equations.