Software QA Testing Question:

In software or software testing, a constant is a meaningful name that represents a number, or string, that does not change. Constants are variables that remain the same, i.e. constant, throughout the execution of a program.
Why do we, developers, use constants? Because if we have code that contains constant values that keep reappearing, or, if we have code that depends on certain numbers that are difficult to remember, we can improve both the readability and maintainability of our code, by using constants.
To give you an example, we declare a constant and we call it "Pi". We set it to 3.14159265, and use it throughout our code. Constants, such as Pi, as the name implies, store values that remain constant throughout the execution of our program.
Keep in mind that, unlike variables which can be read from and written to, constants are read-only. Although constants resemble variables, we cannot modify or assign new values to them, as we can to variables, but we can make constants public or private. We can also specify what data type they are.