Question: I am using an open source project (Open Scene Graph). I found that all the header file names are in `File` format, which I found to be *File With No Extension* as mentioned in some website.

I would like to know why those developer used this extension, rather than the traditional `.h` file extension.

Answer: 
I mailed to one of the developer (Robert Osfield) of OpenSceneGraph. Here is his answer.

> 
> The OSG adopted the same header convention as the standard C++ headers.
>  We have added a -*-C++-*- string to the headers so that editors can
>  use this to determine the type.
> 
> 
>
What I know is that most names were already taken by the C standard library. Since C++ has to co-exist with it, the C++ standard library may have evolved to not have an extension for its headers.

Note that these some of these headers may have the same name, but may or may not be similar in the functionality they offer.

```
#include<some.h> //this includes the header C library
#include<some> //this includes the header from the C++ standard library

```