>>>What is the simplest explanation as to why these are needed? Why not just set regular variable values? So what if they are constant and don't change?
>>
>>Security of the source code so that reverse engineering of an application won't give back that code.
>
>Good additional point.

Give back what code?

It would show "10" instead of "My_Constant" in the source. Is that a big security issue? Enough to not put it in a variable? It can only be done for constants, so constants are the only things that would be protected. Is that a valid security reason to use DEFINE?