Global Variable has global scope and accessible from anywhere in the program. Assigning to global variables from any point in the program has global implications. Global variable are always prefixed with a dollar sign ($). If we want to have a single variable, which is available across classes, we need to define a global variable. By default, an uninitialized global variable has a nil value and its use can cause the programs to be cryptic and complex. Global variable can be change anywhere in program.
$global_variable = 5
Global variable in Class1 is 10 Global variable in Class2 is 10
In above example, a global variable define whose value is 10. This global variable can be access anywhere in the program.
global vars can be used everywhere. See? GFG global vars can be used everywhere. See? GFG, Welcome to GeeksForGeeks
In above example, We define two global variable in a class. we create a object of class Author than call method.