11.3 Operating on the Region

Once you have a region, here are some of the ways you can operate on it:

• Kill it with C-w (see Killing).
• Copy it to the kill ring with M-w (see Yanking).
• Convert case with C-x C-l or C-x C-u (see Case).
• Undo changes within it using C-u C-/ (see Undo).
• Replace text within it using M-% (see Query Replace).
• Indent it with C-x <TAB> or C-M-\ (see Indentation).
• Fill it as text with M-x fill-region (see Filling).
• Print hardcopy with M-x print-region (see Printing).
• Evaluate it as Lisp code with M-x eval-region (see Lisp Eval).
• Save it in a register with C-x r s (see Registers).
• Save it in a buffer or a file (see Accumulating Text).

Most commands that operate on the text in the region have the word region in their names.

Some commands have a default behavior when the mark is inactive, but operate on the text in the region if the mark is active. For example, M-$ (ispell-word) normally checks the spelling of the word at point, but it checks the text in the region if the region is active (see Spelling). Normally, such commands use their default behavior if the region is empty (i.e., if mark and point are at the same position). If you want them to operate on the empty region, change the variable use-empty-active-region to t.

If you enable Delete Selection mode, a minor mode, then inserting text while the mark is active causes the selected text to be deleted first. This also deactivates the mark. Many graphical applications follow this convention, but Emacs does not. To toggle Delete Selection mode on or off, type M-x delete-selection-mode. Another effect of this mode is that some keys, such as <DEL> and C-d, always kill the region if one exists.