What is a file extension at the system level?

Question

Operating Systems

Windows is quite rigidly attached to all kinds of extensions and associates various software with them, in linux there are no file extensions as such, as far as I understand, it's just part of the name.
What is the reason for such a difference in approaches and where can you read about it to figure it out (details are not up to the bytecode level, of course))))

Answer 1

It just happened historically, and is connected not so much with the operating system as with the file system.
In FAT16, the extension was kept separate from the name, and the operating system recognized the extension of executable files in order to run them.
In Windows, they went further - they added associations for other files to which the launch of the software was tied, the associations were stored in the registry and, accordingly, what to launch was determined by the system, regardless of the calling program.
In modern NTFS, the extension is also just part of the name.
In Linux, initially the file system did not store extensions separately, and the launch of the program was parsed by the file header. In addition, the graphical interface appeared much later, and the launch of documents and other non-executable programs by association was done precisely in the graphical interface, and not at the system level - the system itself only works with executable files, for which there is an execute attribute.
That's actually all - that is, it historically arose from the organization of files and the file system.
Both approaches are convenient in their own way.