Each Emacs command behaves in its most general manner, and each option is in its default state. For editing any specific type of text, such as Lisp code or English text, you should switch to the appropriate major mode, such as Lisp mode or Text mode. Selecting a major mode changes the meanings of a few keys to become more specifically adapted to the language being edited. TAB , DEL , and LFD are changed frequently. In addition, commands which handle comments use the mode to determine how to delimit comments.
Many major modes redefine the syntactical properties of characters appearing in the buffer.
See section The Syntax Table . The major modes fall into three major groups. Text mode, Nroff mode, TeX mode, and Outline mode are for editing English text. Most programming language major modes specify that only blank lines separate paragraphs. This is so that the paragraph commands remain useful.