In text display, line wrap is the feature of continuing on a new line when a
line is full, such that each line fits in the viewable window, allowing text to
be read from top to bottom without any horizontal scrolling. Word wrap is the
additional feature of most text editors, word processors, and web browsers, of
breaking lines between and not within words, except when a single word is longer
than a line.

A soft return or soft wrap is the break resulting from line wrap or word wrap
(whether automatic or manual), whereas a hard return or hard wrap is an
intentional break, creating a new paragraph. With a hard enter, paragraph-break
formatting may be applied (either indenting or vertical whitespace). Soft
wrapping allows line lengths to adjust automatically with adjustments to the
width of the user's window or margin settings, and is a standard feature of all
modern text editors, word processors, and email clients. Manual soft breaks are
unnecessary when word wrap is automatically, so hitting the "Enter" key usually
produces a hard return.

Alternatively, "soft enter" can mean an intentional, stored line break that is
not a paragraph break. For example, it is common to print postal addresses in a
multiple-line format, but the several lines are understood to be a single
paragraph. Line breaks are needed to divide the words of the address into lines
of the appropriate length.

In the contemporary graphical word processors Microsoft Word and OpenOffice.org,
users are expected to type a carriage return (enter key) between each paragraph.
Formatting settings, such as first-line indentation or spacing between
paragraphs, take effect where the carriage return marks the break. A
non-paragraph line break, which is a soft return, is inserted using shift-enter
or via the menus, and is provided for cases when the text should start on a new
line but none of the other side effects of starting a new paragraph are desired.

In text-oriented markup languages, a soft return is typically offered as a
markup tag. For example, in HTML there is a <br> tag that has the same purpose
as the soft return in word processors described above; the <p> tag is used to
contain paragraphs.

The Unicode character set provides a line separator character as well as a
paragraph separator to represent the semantics of the soft return and hard
return.

    0x2028 LINE SEPARATOR

    * may be used to represent this semantic unambiguously

    0x2029 PARAGRAPH SEPARATOR

    * may be used to represent this semantic unambiguously

The soft returns are usually placed after the ends of complete words, or after
the punctuation that follows complete words. However, word wrap may also occur
following a hyphen inside of a word. This is sometimes not desired, and can be
blocked by using a non-breaking hyphen, or hard hyphen, instead of a regular
hyphen.

A word without hyphens can be made wrappable by having soft hyphens in it. When
the word isn't wrapped (i.e., isn't broken across lines), the soft hyphen isn't
visible. But if the word is wrapped across lines, this is done at the soft
hyphen, at which point it is shown as a visible hyphen on the top line where the
word is broken. (In the rare case of a word that is meant to be wrappable by
breaking it across lines but without making a hyphen ever appear, a zero-width
space is put at the permitted breaking point(s) in the word.)

Sometimes word wrap is undesirable between adjacent words. In such cases, word
wrap can usually be blocked by using a hard space or non-breaking space between
the words, instead of regular spaces.

In Chinese, Japanese, and Korean, each Han character is normally considered a
word,[citation needed] and therefore word wrapping can usually occur before and
after any Han character.

Under certain circumstances, however, word wrapping is not desired. For
instance,

    word wrapping might not be desired within personal names, and

    word wrapping might not be desired within any compound words (when the text
is flush left but only in some styles).

Most existing word processors and typesetting software cannot handle either of
the above scenarios.

CJK punctuation may or may not follow rules similar to the above-mentioned
special circumstances. It is up to line breaking rules in CJK.

A special case of line breaking rules in CJK, however, always applies: line wrap
must never occur inside the CJK dash and ellipsis. Even though each of these
punctuation marks must be represented by two characters due to a limitation of
all existing character encodings, each of these are intrinsically a single
punctuation mark that is two ems wide, not two one-em-wide punctuation marks.

Word wrapping is an optimization problem. Depending on what needs to be
optimized for, different algorithms are used.

A simple way to do word wrapping is to use a greedy algorithm that puts as many
words on a line as possible, then moving on to the next line to do the same
until there are no more words left to place. This method is used by many modern
word processors, such as OpenOffice.org Writer and Microsoft Word. This
algorithm always uses the minimum possible number of lines but may lead to lines
of widely varying lengths. The following pseudocode implements this algorithm: