02 08 Exploring some PHP Tricks
Dan Gookin's Free PHP Programming Course
Chapter 2, Video 8
A wrap-up of items presented in this chapter includes the 'heredoc', various assignment operators, the useful 'print_r' and 'var_dump' tools (useful for debugging PHP), the exit() and die() functions for leaving a PHP block, and the phpinfo() function, which is helpful for diagnosing and adjusting the PHP installation.
https://www.wambooli.com/php/