Bug or feature: .inc files in page root are automatically displayed

[tires]

I have noticed some strange behavior. If I have a file in the root of the page called e.g. mypage.inc, it is displayed when I call up the url "myurl.de/mypage". Is this a bug or a feature?

[tires]

Sorry, a made an error in thinking.
There is a directory in the root with this name containing an index.html file.