How do I execute (“evaluate”) a piece of Emacs Lisp code?

There are a number of ways to execute (evaluate, in Lisp lingo) an Emacs Lisp form:

• If you want it evaluated every time you run Emacs, put it in a file named .emacs.d/init.el in your home directory. This is known as “your init file,” and contains all of your personal customizations (see How do I set up an init file properly?).

• You can type the form in the *scratch* buffer, and then type LFD (or C-j) after it. The result of evaluating the form will be inserted in the buffer.

• In emacs-lisp-mode, typing C-M-x evaluates a top-level form before or around point.

• Typing C-x C-e in any buffer evaluates the Lisp form immediately before point and prints its value in the echo area.

• Typing M-: or M-x eval-expression allows you to type a Lisp form in the minibuffer which will be evaluated once you press RET.

• You can use M-x load-file to have Emacs evaluate all the Lisp forms in a file. (To do this from Lisp use the function load instead.)

  The functions load-library, eval-region, eval-buffer, require, and autoload are also useful; see Where can I get documentation on Emacs Lisp?, if you want to learn more about them.