Any reason for prefix in class members?

[MatthewRock]

Hello,
I'm wondering if there is any reason for using prefix in class member's name.

I mean something like this:

class Example
{
 //code....

 //Syntax:
 typename letter_memberName;

 //example:
 int m_value;

 //code...
};

Not only I encountered this in some code I read, but also class creator in my IDE has an option of adding prefix. What's the purpose of prefix?

[AlitCandle]

http://i.imgur.com/YuyNXuD.png

It doesn't actually do anything. You should put it in your code to make it more readable.