Emacs for Humans: Glossary
I have noticed while learning and teaching Emacs that there are some words Emacs people use in ways that are not immediately obvious to non-Emacs people. Here’s a short glossary I constructed for my own personal use.
You’re not meant to read this document from top to bottom. Just look up whatever weird terminology is confusing you. I’m also going to link to this document in other articles whenever I use these words.
Buffer
An open document. A buffer is a bunch of characters, stored in primary memory1 also known, somewhat sloppily, as RAM and accessible in Emacs. It’s important to note that while a buffer does not have to correspond to a file on disk2 pretty much anything you see on screen in Emacs is displayed in a buffer., it can always be treated as if it were: it can be modified, saved, reverted and so on. See also scratch buffer.
Face
Font. As in the combination of font family, font weight, font variant, text colour and so on. The way characters appear on screen.
Major mode
The dominating behaviour of Emacs is determined by the major mode. I use the determinate article3 “the” because there can only be a single major mode active in a buffer. When editing files, the major mode is frequently determined by the file type: C source code uses CC mode, Org files uses Org mode, directories use Dired mode, the built-in help files uses Help mode, pdf files use docview mode, and so on.
Emacs major modes are somewhat similar to what modern ide tools call “perspectives”.
The major mode can often be extensively configured to suit your preferences. Additional major modes can be installed or created by yourself. You can define “derived” major modes which inherit most of their behaviour from their parent mode.
Minor mode
Minor modes are probably what most people intuitively think of when they hear about “Emacs modes”. Minor modes are like small suites of related functionalities (keyboard shortcuts, extra text highlighting, editing commands, information displays, spell checkers, fuzzy finders, and so on) which can be toggled on or off at will.
Minor modes can be either global (which means they are toggled on or off simultaneously for all open s) or local (which means that if you turn them on for one buffer, they remain turned off in all other buffers.)
Mode
This is a tough one. Mode actually refers to two different4 there is a glancing relationship, but it is barely worth mentioning things depending on whether you are talking about a major mode or a minor mode. See those entries for an explanation of each.
Scratch buffer
A new, blank document. What other applications call “create new document”, Emacs
people call “open scratch buffer”. You get a new scratch buffer by pressing C-x
b5 to switch to a different buffer and then typing in a buffer name that
does not correspond to any currently open file.