Punctuation Names Table

Formally, the number sign - that is the Unicode name, and in American usage pound sign means the same mark (which collides with the British pound sign, the £ currency symbol). Its most storied alias is octothorpe, a Bell Labs invention from the 1960s touch-tone keypad project; the octo- is said to reference the eight points around the central square, while thorpe remains genuinely unexplained - one of its inventors joked it honored the athlete Jim Thorpe. British usage says hash, which is how the mark entered telephone prompts as the hash key; and since 2007 the social form hashtag has given this centuries-old commercial mark (a contraction of the weight unit pound, drawn as ℔ with crossed strokes) its most famous job. So: number sign to a standards document, octothorpe to a telephone historian, hash in London, pound in Chicago, hashtag online - all one shape.

The ^ is the caret (its freestanding form is circumflex accent in Unicode): on typewriters it was the proofreader's insertion mark, meaning put something here; in programming it is usually the XOR operator or the exponent in calculators, and in regular expressions it anchors the start of a line. Its name comes from Latin caret, it is lacking - literally the word proofreaders wrote in the margin. The ~ is the tilde, another typewriter refugee: Spanish ñ and Portuguese ã needed a squiggle over letters the machine could not print, so the freestanding tilde did the job before dedicated keys existed (that is why its Unicode name insists on freestanding). In math it means approximately equal, in Unix home directories, and in casual text, roughly or kinda - a punctuation mark whose whole career is about not-quite-precision.

It is the pipe - formally vertical line in Unicode, with bar and vertical bar as working aliases. The name comes straight from Unix: the vertical bar pipes the output of one command into the input of the next, and the plumbing metaphor stuck so well that almost every command-line tradition adopted both the character and the word. Its other jobs doubled alongside: alternation in regular expressions (cat|dog matches either), the logical OR in several programming languages as a double bar (||), and in markdown tables it draws the column dividers. Before computing, a vertical stroke was just that - the printing trade had little use for it, which is why the pipe is one of the few keyboard characters whose everyday name is entirely a software-era invention. Say pipe to any programmer and vertical bar to any standards document; both will know exactly what you drew.

The straight quote (" - formally quotation mark, colloquially ditto, inch mark or double prime to typographers) is the typewriter's compromise: one key, two jobs, no curvature because the typebar struck straight down. The curly pair - left and right double quotation marks - is what professional printing always used, and what word processors now insert automatically as smart quotes: shapes that actually indicate opening versus closing. The trouble is that software treats them as different characters entirely: code, file paths, and anything typed into a terminal want the straight ASCII quote, and a smart-quote smuggled in from a word processor breaks the command invisibly. Typographers add one more distinction worth knowing: prime marks (prime and double prime) look like straight quotes but mean feet and inches in measurements - 6'2" is read six feet two inches, and setting it with true primes instead of quote marks is one of those small marks of care that separates typeset text from typed text.