Sometimes, a line of text in the buffer—a logical line—is too long to fit in the window, and Emacs displays it as two or more screen lines. This is called line wrapping or continuation, and the long logical line is called a continued line. On a graphical display, Emacs indicates line wrapping with small bent arrows in the left and right window fringes. On a text terminal, Emacs indicates line wrapping by displaying a ‘\’ character at the right margin.
Most commands that act on lines act on logical lines, not screen
lines. For instance, C-k kills a logical line. As described
earlier, C-n (
next-line) and C-p
previous-line) are special exceptions: they move point down
and up, respectively, by one screen line (see Moving Point).
Emacs can optionally truncate long logical lines instead of continuing them. This means that every logical line occupies a single screen line; if it is longer than the width of the window, the rest of the line is not displayed. On a graphical display, a truncated line is indicated by a small straight arrow in the right fringe; on a text terminal, it is indicated by a ‘$’ character in the right margin. See Line Truncation.
By default, continued lines are wrapped at the right window edge. Since the wrapping may occur in the middle of a word, continued lines can be difficult to read. The usual solution is to break your lines before they get too long, by inserting newlines. If you prefer, you can make Emacs insert a newline automatically when a line gets too long, by using Auto Fill mode. See Filling.
Sometimes, you may need to edit files containing many long logical
lines, and it may not be practical to break them all up by adding
newlines. In that case, you can use Visual Line mode, which enables
word wrapping: instead of wrapping long lines exactly at the
right window edge, Emacs wraps them at the word boundaries (i.e.,
space or tab characters) nearest to the right window edge. Visual
Line mode also redefines editing commands such as
C-k to operate on screen lines rather than
logical lines. See Visual Line Mode.