A little while back Matthew Turland posted about something that some developers moving over to PHP from more strict languages have an issue with - variable typing - and how its evolved in languages over time.

Without a little background in programming languages or computer science in general, it's entirely possible that typing systems are not something that have crossed your mind. I thought I'd take a blog entry to share some of my thoughts on how it’s affecting the creation and evolution of languages.

He walks through history a bit, mentioning C, Java, Python and PHP and how they differ in their default type handling. He especially focuses on the "blurred line" between strong and weak typing and how some if offers special features to the language that uses the method.