Linux typically doesn't rely on file extensions; it gets a files type using "magic numbers" within the file itself. Linux apps, including GNOME Files, may still use extensions to determine file type.

In the Linux environment, the file system acts as a backbone, orchestrating the systematic storage and retrieval of data. It is a hierarchical structure that outlines how data is organized, stored, ...

There's a lot to learn about image files on the command line, from verifying file format to finding out where and when photos were taken and maybe even getting an unusual view of what they look like.