2 types. Text and binary files. Images, sounds, compiled programs, videos are all binary files. Some word processors save their work in binary files.

Text files can follow all sorts of syntaxes. Plaintext, HTML, JSON and so on.

There are two: text files which are human readable when opened in a text editor, and binary files which aren't.

There's all kinds of files.

Executable programs, libraries, disk images, compressed archives, symbolic links, device nodes, pipes, the list goes on.

There are also “blobs,” or simply “other” files which are intended to be machine-readable. But that’s getting down into the weeds a bit.

.txt and .docx are both text - the latter just has additional text that’s intended for the program to help display said text in various ways.

I was having this exact same conversation down the pub the other day...