Do not open any file that includes .php on its address. They come through with some regularity and often claim to be "As seen on Oprah." As I have never opened one, I am not sure what kind of malware they contain but I would rather be safe and suspicious than a victim.

php is the most widely used server side scripting language on the Internet. Wikipedia estimates that in 2014, 82% of websites (where the server language is known) are using php.

OK a lot of sites hide the extension from the user these days but most people will viewing sites that use php every day. Wikipedia, Facebook, Wordpress, etc. all make use of php.

That said, you really do not want to opening "As seen on Oprah.". That would be the case even it there was no extension of the extension was say .cfm (Cold Fusion - what Mudcat uses).