Why do directory listings contain the current (.) and parent (..) directory?

Question

Whenever I list the contents of a directory with a function like readdir, the returned file names also include \".\" and \"..\". I have the suspicion that these are just nor

Answer 1

One reason is that without them there is no way to get to the parent directory. Or get a handle to the current directory.

Without them, we cannot do such things as:

./run_this

Indeed, we couldn't add '.' to the $PATH, meaning we couldn't ever execute files that weren't already in the path.