This article explains what a text file is and how to open a text file or convert it to another format.
Text Files (Part 1) What is a text file?
A text file is a file that contains text. There are different ways to understand that. Therefore, it is important to know what kind of text document you have before you start working with a program that can open or convert it.
In general, a text file refers to a file that contains only text and no images or other non-text characters. These sometimes use the TXT file extension, but they don't have to. For example, a Word document that is an essay with only text could be in the DOCX file format and still be called a text file.
I've even seen semi-text-only files being referred to as text files, simply because the bulk of the document is actually text. Back to the DOCX example, if the file contained a few charts and a few photos, some people might still call it a text document.