Semantics ~ Meaning Syntax ~ Symbolic representation So two programs written in different languages could do the same thing (semantics) but the symbols used to write the program would be different (syntax). A compiler will check your syntax for you (compile-time errors), and derive the semantics from the language rules (mapping the syntax to machine instructions say), but won't find all the semantic errors (run-time errors, e.g. calculating the wrong result because the code says add 1 instead of add 2).