What is the file extension when creating Binary files

Question

I am just trying to learn to write to Binary files. When we create text files we normally give the extension .txt. The same way, what should be the file extension for Binary files created using C#.

Which are the contexts that demands us to write to a binary file. What is the benefit in writing/creating a binary file rather than a text file when processing data?

Answer 1

Absolutely anything you want, or even nothing at all.

Just make sure you're consistent, and it helps not to use an extension already in wide use such as .doc or .pdf

Microsoft once advised using long extensions of the form .company-program-format [1] since you can have extensions longer than 3 characters now, but this never took off to gain wide acceptance in the industry.

1: Footnote: I cannot find a source for this claim but I remember reading it on MSDN around the time Windows Vista came out. You see it in Windows OS files like dvr-ms. These former guidelines are alluded to in this page, but the it's link is now broken and points to a totally different page: https://msdn.microsoft.com/en-gb/library/windows/desktop/cc144156(v=vs.85).aspx#short_and_long

Answer 2

From my experience, .BIN and .DAT are the most popular extensions for "raw" binary file formats.

But it's just a general convention, you are not limited to follow it in your own projects.