It argues that it operates as an interpreter, in exactly the way that I described. From your link, The Zend Engine compiles PHP source code on-the-fly into an

It argues that it operates as an interpreter, in exactly the way that I described. From your link, The Zend Engine compiles PHP source code on-the-fly into an internal format that it can execute, thus it works as an interpreter. In other works at startup itreads code, compiles to an internal form of byte code, and from then on it executes that. So it works as an interpreter (you give it code, it runs). But internally it does not go line by line as you go. As a simple demonstration, a syntax error on line 10 of a PHP script will keep it from executing code on line 5. By contrast a syntax error on line 10 of a Bash script will not keep it from having executed line 5 first.