| ` | |
|---|---|
Backtick | |
| In Unicode | U+0060 `GRAVE ACCENT (symbol) |
| Related | |
| See also | U+0300 ◌̀COMBINING GRAVE ACCENT (diacritic) |
Thebacktick` is atypographical mark used mainly incomputing. It is also known asbackquote,grave, orgrave accent.
The character was designed for typewriters to add a grave accent to a (lower-case[a]) base letter, by overtyping it atop that letter.[1] On early computer systems, however, this physicaldead key+overtype function was rarely supported, being functionally replaced byprecomposed characters.[b] Consequently, thisASCII symbol was rarely (if ever) used in computer systems for its original aim and became repurposed in computer programming for many unrelated uses.
The sign is located on the left-top of a US or UK layout keyboard, next to the1 key. Provision (if any) of the backtick on other keyboards varies by nationalkeyboard layout andkeyboard mapping. In layouts that use thedead key concept, the backtick key is most frequently chosen for that purpose.
On typewriters designed for languages that routinely usediacritics (accent marks), there are two possible solutions. Keys can be dedicated to pre-composed characters or alternatively adead key mechanism can be provided. With the latter, a mark is made when a dead key is typed but, unlike normal keys, the paper carriage does not move on and thus, the next letter to be typed is printed under the accent.
The incorporation of the grave symbol into ASCII is a consequence of this prior existence on typewriters. This symbol did not exist independently as atype orhot-lead printing character.
It appears to have been at their May 13–15, 1963 meeting that the CCITT decided that the proposed ISO 7-bit code standard would be suitable for their needs if a lower case alphabet and five diacritical marks, including the grave accent, were added to it. At the October 29–31 meeting, then, the ISO subcommittee altered the ISO draft to meet the CCITT requirements, replacing the up-arrow and left-arrow with diacriticals, adding diacritical meanings to the apostrophe and quotation mark, and making the number sign a dual for the tilde.[2]
— Yucca's free information site
Thus, ISO 646 was born and the ASCII standard updated to include the backtick and other symbols.[c]
Some early ASCII peripherals designed the backtick and apostrophe to be mirror images of each other:‛ and’.[3] This allowed them to be used as matching pairs of open and close quotes while still being somewhat usable as grave and acute accents, made apostrophes typographically correct, and allowed the apostrophe to be used as a prime. This had a number of problems that led most modern systems and Unicode to render the apostrophe as a "straight" one:
This can still be seen in documents and email from that time (before 1990), and in output generated by some UNIX console programs such asman pages. Institutions that traditionally had used it have abandoned or deprecated it.[4][5]
On computer keyboards with a suitablekeyboard layout ('keyboard mapping'), the` acts as adead key. When pressed, it has no immediate effect – its effect is to apply adiacritic to the next key pressed.
Manycommand-line interface languages and thescripting (programming) languages likePerl,PHP,Ruby andJulia (though see below) use pairs of backticks to indicatecommand substitution. A command substitution is thestandard output from one command, into an embedded line of text within another command.[6][7] For example, using $ as the symbol representing a terminal prompt, the code line:
$echo"It is now `date`"It is now Tue Feb 17 07:37:49 UTC 2026
In all POSIXshells (includingBash andZsh), the use of backticks for command substitution is now largely deprecated[citation needed] in favor of the notation$(...), so that the example above would be re-written:
$echo"It is now$(date)"
The new syntax allows nesting, for example:
$echo"An absolute path to the 'zcat' command is$(readlink-e"$(type-Pzcat)")"An absolute path to the 'zcat' command is /usr/bin/gzip
It is sometimes used insource code comments to indicate code, e.g.,
/* Use the `printf()` function. */
This is also the format theMarkdown formatter uses to indicate code.[8] Some variations of Markdown support "fenced code blocks" that span multiple lines of code, starting (and ending) with three backticks in a row (```).[9]
` is rendered as single opening curly quote (‘) and`` is a double curly opening quote (“). It also supplies the numeric ASCII value of an ASCII character wherever a number is expected.name andpet variable's values get substituted into the string enclosed by grave accent characters:constname="Mary",pet="lamb";// Set variableslettemp=`${name} has a little${pet}!`;console.log(temp);// => "Mary has a little lamb!";
$ inside double quotes.Cmd, that can be run, with run function, likerun(`echo Hello world!`). You can interpolate Julia variables, but only indirectly shell environment variables.`n. Most common programming languages use a backslash as the escape character (e.g.,\n), but because Windows allows the backslash as a path separator, it is impractical for PowerShell to use backslash for a different purpose. Two backticks produce the` character itself. For example, thenullableboolean of.NET is specified in PowerShell as[Nullable``1[System.Boolean]].repr() function, which converts its argument to a string suitable for a programmer to view. However, this feature was removed in Python 3.0. Backticks also appear extensively in thereStructuredText plain text markup language (implemented in the Pythondocutils package).In many PC-based computer games in the US and UK, the` key is used to open theconsole so the user can execute script commands via itsCLI.[citation needed] This is true for games such asFactorio,Battlefield 3,Half-Life,Halo CE,Quake,Half-Life 2,Blockland,Soldier of Fortune II: Double Helix,Unreal,Counter-Strike,Crysis,Morrowind,Oblivion,Skyrim,[13]Fallout: New Vegas,Fallout 3,Fallout 4,RuneScape, and games based on theQuake engine orSource engine.[citation needed]While not necessarily the original progenitor of the console key concept,Quake is still widely associated with any usage of the` key as a toggle for a drop-down console, often being referred to as the "Quake Key". In 2021,Windows Terminal introduced a "Quake Mode" which enables a global shortcut of⊞ Win+` that opens a terminal window pinned to the top half of the screen.[14]
This key is on German typewriters a non-spacing key (DIN 2137). It does not advance the cursor, but causes the next character to appear below the accent
Please do not use the ASCII grave accent as a left quotation mark
In the C locale, the output of GNU programs should stick to plain ASCII for quotation characters in messages to users: preferably 0x22 (‘"’) or 0x27 (‘'’) for both opening and closing quotes. Although GNU programs traditionally used 0x60 (‘`’) for opening and 0x27 (‘'’) for closing quotes, nowadays quotes ‘`like this'’ are typically rendered asymmetrically, so quoting ‘"like this"’ or ‘'like this'’ typically looks better.