# Less-than sign

The less-than sign is a mathematical symbol that denotes an inequality between two values. The widely adopted form of two equal-length strokes connecting in an acute angle at the left, <, has been found in documents dated as far back as the 1560s. In mathematical writing, the less-than sign is typically placed between two values being compared and signifies that the first number is less than the second number. Examples of typical usage include 1⁄2 < 1 and −2 < 0.
Since the development of computer programming languages, the less-than sign and the greater-than sign have been repurposed for a range of uses and operations.

## Computing

The less-than sign, <, is an original ASCII character (hex 3C, decimal 60).

### Programming

In BASIC, Lisp-family languages, and C-family languages (including Java and C++), comparison operator < means "less than".
In Coldfusion, operator .lt. means "less than".
In Fortran, operator .LT. means "less than"; later versions allow <.

#### Shell scripts

In Bourne shell (and many other shells), operator -lt means "less than". Less-than sign is used to redirect input from a file. Less-than plus ampersand (<&) is used to redirect from a file descriptor.

#### Double less-than sign

The double less-than sign, <<, may be used for an approximation of the much-less-than sign (≪) or of the opening guillemet («). ASCII does not encode either of these signs, though they are both included in Unicode.
In Bash, Perl, and Ruby, operator <<EOF (where "EOF" is an arbitrary string, but commonly "EOF" denoting "end of file") is used to denote the beginning of a here document.
In C and C++, operator << represents a binary left shift.
In the C++ Standard Library, operator <<, when applied on an output stream, acts as insertion operator and performs an output operation on the stream.
In Ruby, operator << acts as append operator when used between an array and the value to be appended.
In XPath the << operator returns true if the left operand precedes the right operand in document order; otherwise it returns false.

#### Triple less-than sign

In PHP, operator <<<OUTPUT is used to denote the beginning of a heredoc statement (where OUTPUT is an arbitrary named variable.)
In Bash, <<<word is used as a "here string", where word is expanded and supplied to the command on its standard input, similar to a heredoc.

#### Less-than sign with equals sign

The less-than sign with the equals sign, <=, may be used for an approximation of the less-than-or-equal-to sign, ≤. ASCII does not have a less-than-or-equal-to sign, but Unicode defines it at code point U+2264.
In BASIC, Lisp-family languages, and C-family languages (including Java and C++), operator <= means "less than or equal to". In Sinclair BASIC it is encoded as a single-byte code point token.
In Prolog, =< means "less than or equal to" (as distinct from the arrow <=).
In Fortran, operators .LE. and <= both mean "less than or equal to".
In Bourne shell and Windows PowerShell, the operator -le means "less than or equal to".

#### Less-than sign with hyphen-minus

In the R programming language, the less-than sign is used in conjunction with a hyphen-minus to create an arrow (<-), this can be used as the left assignment operator.

#### Spaceship operator

The less-than sign is used in the spaceship operator.

#### HTML

In HTML (and SGML and XML), the less-than sign is used at the beginning of tags. The less-than sign may be included with &lt;. The less-than-or-equal-to sign, ≤, may be included with &le;.

## Unicode

Unicode provides various Less Than Symbols:
| Symbol | Unicode name | Code Point |
| < | LESS-THAN SIGN | U+003C |
| ≤ | LESS-THAN OR EQUAL TO | U+2264 |
| ≦ | LESS-THAN OVER EQUAL TO | U+2266 |
| ≨ | LESS-THAN BUT NOT EQUAL TO | U+2268 |
| ≪ | MUCH LESS-THAN | U+226A |
| ≮ | NOT LESS THAN | U+226E |
| ≰ | NEITHER LESS-THAN NOR EQUAL TO | U+2270 |
| ≲ | LESS-THAN OR EQUIVALENT TO | U+2272 |
| ≴ | NEITHER LESS-THAN NOR EQUIVALENT TO | U+2274 |
| ⋖ | LESS-THAN WITH DOT | U+22D6 |
| ⋘ | VERY MUCH LESS-THAN | U+22D8 |
| ⋜ | EQUAL TO OR LESS-THAN | U+22DC |
| ⋦ | LESS-THAN BUT NOT EQUIVALENT TO | U+22E6 |
| ⍃ | APL FUNCTIONAL SYMBOL QUAD LESS-THAN | U+2343 |
| ⥶ | LESS-THAN ABOVE LEFTWARDS ARROW | U+2976 |
| ⥷ | LEFTWARDS ARROW THROUGH LESS-THAN | U+2977 |
| ⦓ | LEFT ARC LESS-THAN BRACKET | U+2993 |
| ⦖ | DOUBLE RIGHT ARC LESS-THAN BRACKET | U+2996 |
| ⧀ | CIRCLED LESS-THAN | U+29C0 |
| ⩹ | LESS-THAN WITH CIRCLE INSIDE | U+2A79 |
| ⩻ | LESS-THAN WITH QUESTION MARK ABOVE | U+2A7B |
| ⩽ | LESS-THAN OR SLANTED EQUAL TO | U+2A7D |
| ⩿ | LESS-THAN OR SLANTED EQUAL TO WITH DOT INSIDE | U+2A7F |
| ⪁ | LESS-THAN OR SLANTED EQUAL TO WITH DOT ABOVE | U+2A81 |
| ⪃ | LESS-THAN OR SLANTED EQUAL TO WITH DOT ABOVE RIGHT | U+2A83 |
| ⪅ | LESS-THAN OR APPROXIMATE | U+2A85 |
| ⪇ | LESS-THAN AND SINGLE-LINE NOT EQUAL TO | U+2A87 |
| ⪉ | LESS-THAN AND NOT APPROXIMATE | U+2A89 |
| ⪍ | LESS-THAN ABOVE SIMILAR OR EQUAL | U+2A8D |
| ⪕ | SLANTED EQUAL OR LESS-THAN | U+2A95 |
| ⪗ | SLANTED EQUAL OR LESS-THAN WITH DOT INSIDE | U+2A97 |
| ⪙ | DOUBLE-LINE EQUAL TO OR LESS-THAN | U+2A99 |
| ⪛ | DOUBLE-LINE SLANTED EQUAL TO OR LESS-THAN | U+2A9B |
| ⪝ | SIMILAR TO OR LESS-THAN | U+2A9D |
| ⪟ | SIMILAR ABOVE LESS-THAN ABOVE EQUALS SIGN | U+2A9F |
| ⪡ | DOUBLE NESTED LESS-THAN | U+2AA1 |
| ⪣ | DOUBLE NESTED LESS-THAN WITH UNDERBAR | U+2AA3 |
| ⪦ | LESS-THAN CLOSED BY CURVE | U+2AA6 |
| ⪨ | LESS-THAN CLOSED BY CURVE ABOVE SLANTED EQUAL | U+2AA8 |
| ⫷ | TRIPLE NESTED LESS-THAN | U+2AF7 |
| ⫹ | DOUBLE-LINE SLANTED LESS-THAN OR EQUAL TO | U+2AF9 |
| ﹤ | SMALL LESS-THAN SIGN | U+FE64 |
| ＜ | FULLWIDTH LESS-THAN | U+FF1C |
The less-than sign may be seen for an approximation of the opening angle bracket, ⟨. True angle bracket characters, as required in linguistics notation, are expected in formal texts.

## Mathematics

In an inequality, the less-than sign and greater-than sign always "point" to the smaller number. Put another way, the "jaws" (the wider section of the symbol) always direct to the larger number.
The less-than-sign is sometimes used to represent a total order, partial order or preorder. However, the symbol $\prec$ is often used when it would be confusing or not convenient to use <. In mathematical writing using LaTeX, the TeX command is \prec. The Unicode code point is U+227A ≺ PRECEDES.