The purpose of using plain text today is primarily independence from programs that require their very own special encoding or formatting or file format. Plain text files can be opened, read, and edited with ubiquitous text editors and utilities.

Why you should use plain text?

Plain text files are at the zenith of ease of use. There isn't really anything to learn; you just start typing text into a blank file. That's it. No keyboard shortcuts to learn, or complicated menu structures, or ways to format etc.

What does make plain text do?

To put it simply, plain text is any text that isn't formatted. It does not take any special formatting, such as varying fonts, font sizes, bold font, or italics. It also only contains standard characters, which are those found in the default set of characters that an application can display.