PHP Global keyword, $GLOBALS array, and modifying a global variable by reference

Discussing the difference between global and local function variables and how to modify them within PHP. 3 topics are discussed:

i) The global keyword (0:00)
ii) the $GLOBALS array, where php stores all global variables (3:57)
iii) passing a global variable by reference into a function to alter its value(8:00)

references:

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