Differentiate between variables and constants in PHP

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Few difference between variables and constants in PHP are given below:

Variables	Constants
The value of a variable can be CHANGED during the execution.	The constant value can’t be changed during script execution.
Variables require COMPULSORY usage of the $ sign at the start.	No dollar sign ($) is REQUIRED before using a constant.
It is possible to define a variable by simple assignment.	Constants can’t be defined by simple assignments. They are defined using the define() function.
The default scope is the current ACCESS scope.	Constants can be accessed throughout without any scoping rules.

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