Some folks like to see a visual indicator of the file type in file listings. In Emacs, this usually means in the Dired listings. Probably the best known way of doing this is the all-the-icons-dired package. It has a set of beautiful icons that it adds to each entry to identify the file type. The problem, from some people’s point of view, is that all-the-icons-dired is a third party package and may, in turn, require the installation of additional font files.
James Dyer likes the idea of a visual file-type indicator but doesn’t like having to deal with external packages and their dependencies. His solution is a light-weight version of a visual icon package. Actually, it’s not even a package, just a bit of code that you can add to your init.el to implement his solution.
The “icons” are just standard shapes that are in virtually all font sets. They aren’t as pretty as those in all-the-icons-dired but they do serve to provide a visual indicator of file type. The shapes are listed in a simple variable so you can change them to suit your needs.
Being an old-time guy who spent a lot of years working on text terminals, I have no problem distinguishing file types by their extension—which is, after all, what all these packages do—so I don’t feel the need for such a solution but if the idea appeals to you and you don’t want to deal with dependencies, give Dyer’s post a look. It’s simple to try out and if you don’t like it you can just delete the code from your init.el.