Property overloading continues to protect properties by forcing access and manipulation through public methods, yet allowing the data to be accessed as if it were a public property. These methods, known as accessors and mutators, or more informally as getters and setters, are automatically triggered whenever the property is accessed or manipulated, respectively.

Thare are two functions are used to add file in a script
1.The include()function
2.The require() function

The action attribute determines where to send the form-data in the form submission.

This function is used to determine if a variable is set and is not NULL

passing arguments by value:Means any changes made to those values within the scope of the function are ignored outside of the function.
passing arguments by reference:Means any changes made to those values within the scope of the function are reflected outside of the function.