Western Antiquity

Most texts were still written in scriptura continua, that is without any separation between words. However, the Greeks were sporadically using punctuation marks consisting of vertically arranged dots—usually two (dicolon) or three (tricolon)—in around the 5th century BC as an aid in the oral delivery of texts. After 200 BC, the Greeks used Aristophanes of Byzantium's system (called théseis) of a single dot (punctus) placed at varying heights to mark up speeches at rhetorical divisions:

• hypostigmḗ – a low punctus on the baseline to mark off a komma (unit smaller than a clause);
• stigmḕ mésē – a punctus at midheight to mark off a clause (kōlon); and
• stigmḕ teleía – a high punctus to mark off a sentence (periodos).^[8]

In addition, the Greeks used the paragraphos (or gamma) to mark the beginning of sentences, marginal diples to mark quotations, and a koronis to indicate the end of major sections.

The Romans (c. 1st century BC) also occasionally used symbols to indicate pauses, but the Greek théseis—under the name distinctiones^[9]—prevailed by the 4th century AD as reported by Aelius Donatus and Isidore of Seville (7th century). Also, texts were sometimes laid out per capitula, where every sentence had its own separate line. Diples were used, but by the late period these often degenerated into comma-shaped marks.

Medieval

Punctuation developed dramatically when large numbers of copies of the Bible started to be produced. These were designed to be read aloud, so the copyists began to introduce a range of marks to aid the reader, including indentation, various punctuation marks (diple, paragraphos, simplex ductus), and an early version of initial capitals (litterae notabiliores). Jerome and his colleagues, who made a translation of the Bible into Latin, the Vulgate (c. AD 400), employed a layout system based on established practices for teaching the speeches of Demosthenes and Cicero. Under his layout per cola et commata every sense-unit was indented and given its own line. This layout was solely used for biblical manuscripts during the 5th–9th centuries but was abandoned in favor of punctuation.

In the 7th–8th centuries Irish and Anglo-Saxon scribes, whose native languages were not derived from Latin, added more visual cues to render texts more intelligible. Irish scribes introduced the practice of word separation.^[10] Likewise, insular scribes adopted the distinctiones system while adapting it for minuscule script (so as to be more prominent) by using not differing height but rather a differing number of marks—aligned horizontally (or sometimes triangularly)—to signify a pause's duration: one mark for a minor pause, two for a medium one, and three for a major one. Most common were the punctus, a comma-shaped mark, and a 7-shaped mark (comma positura), often used in combination. The same marks could be used in the margin to mark off quotations.

In the late 8th century a different system emerged in France under the Carolingian dynasty. Originally indicating how the voice should be modulated when chanting the liturgy, the positurae migrated into any text meant to be read aloud, and then to all manuscripts. Positurae first reached England in the late 10th century, probably during the Benedictine reform movement, but was not adopted until after the Norman conquest. The original positurae were the punctus, punctus elevatus,^[11] punctus versus, and punctus interrogativus, but a fifth symbol, the punctus flexus, was added in the 10th century to indicate a pause of a value between the punctus and punctus elevatus. In the late 11th/early 12th century the punctus versus disappeared and was taken over by the simple punctus (now with two distinct values).^[12]

The late Middle Ages saw the addition of the virgula suspensiva (slash or slash with a midpoint dot) which was often used in conjunction with the punctus for different types of pauses. Direct quotations were marked with marginal diples, as in Antiquity, but from at least the 12th century scribes also began entering diples (sometimes double) within the column of text.

Printing-press era

The amount of printed material and its readership began to increase after the invention of moveable type in Europe in the 1450s. Martin Luther's German Bible translation was one of the first mass printed works, he used only virgule, full stop and less than one percent question marks as punctuation. The focus of punctuation still was rhetorical, to aid reading aloud.^[13] As explained by writer and editor Lynne Truss, "The rise of printing in the 14th and 15th centuries meant that a standard system of punctuation was urgently required."^[14] Printed books, whose letters were uniform, could be read much more rapidly than manuscripts. Rapid reading, or reading aloud, did not allow time to analyze sentence structures. This increased speed led to the greater use and finally standardization of punctuation, which showed the relationships of words with each other: where one sentence ends and another begins, for example.

The introduction of a standard system of punctuation has also been attributed to the Venetian printers Aldus Manutius and his grandson. They have been credited with popularizing the practice of ending sentences with the colon or full stop (period), inventing the semicolon, making occasional use of parentheses, and creating the modern comma by lowering the virgule. By 1566, Aldus Manutius the Younger was able to state that the main object of punctuation was the clarification of syntax.^[15]

By the 19th century, punctuation in the Western world had evolved "to classify the marks hierarchically, in terms of weight".^[16] Cecil Hartley's poem identifies their relative values:

The use of punctuation was not standardised until after the invention of printing. According to the 1885 edition of The American Printer, the importance of punctuation was noted in various sayings by children, such as:

With a semi-colon and a comma added, it reads as follows:

In a 19th-century manual of typography, Thomas MacKellar writes:

Shortly after the invention of printing, the necessity of stops or pauses in sentences for the guidance of the reader produced the colon and full point. In process of time, the comma was added, which was then merely a perpendicular line, proportioned to the body of the letter. These three points were the only ones used until the close of the fifteenth century, when Aldo Manuccio gave a better shape to the comma, and added the semicolon; the comma denoting the shortest pause, the semicolon next, then the colon, and the full point terminating the sentence. The marks of interrogation and admiration were introduced many years after.^[19]

Typewriters and electronic communication

The introduction of electrical telegraphy with a limited set of transmission codes^[20] and typewriters with a limited set of keys influenced punctuation subtly. For example, curved quotes and apostrophes were all collapsed into two characters (' and "). The hyphen, minus sign, and dashes of various widths have been collapsed into a single character (-), sometimes repeated to represent a long dash. The spaces of different widths available to professional typesetters were generally replaced by a single full-character width space, with typefaces monospaced. In some cases a typewriter keyboard did not include an exclamation point (!), which could otherwise be constructed by the overstrike of an apostrophe and a period; the original Morse code did not have an exclamation point.

These simplifications have been carried forward into digital writing, with teleprinters and the ASCII character set essentially supporting the same characters as typewriters. Treatment of whitespace in HTML discouraged the practice (in English prose) of putting two full spaces after a full stop, since a single or double space would appear the same on the screen. (Most style guides now discourage double spaces, and some electronic writing tools, including Wikipedia's software, automatically collapse double spaces to single.) The full traditional set of typesetting tools became available with the advent of desktop publishing and more sophisticated word processors. Despite the widespread adoption of character sets like Unicode that support the punctuation of traditional typesetting, writing forms like text messages tend to use the simplified ASCII style of punctuation, with the addition of new non-text characters like emoji. Informal text speak tends to drop punctuation when not needed, including some ways that would be considered errors in more formal writing.

In the computer era, punctuation characters were recycled for use in programming languages and URLs. Due to its use in email and Twitter handles, the at sign (@) has gone from an obscure character mostly used by sellers of bulk commodities (10 pounds @$2.00 per pound), to a very common character in common use for both technical routing and an abbreviation for "at". The tilde (~), in moveable type only used in combination with vowels, for mechanical reasons ended up as a separate key on mechanical typewriters, and like @ it has been put to completely new uses.

Interrobang

In 1962, American advertising executive Martin K. Speckter proposed the interrobang (‽), a combination of the question mark and exclamation point, to mark rhetorical questions or questions stated in a tone of disbelief. Although the new punctuation mark was widely discussed in the 1960s, it failed to achieve widespread use.^[27] Nevertheless, it and its inverted form were given code points in Unicode: U+203D ‽ INTERROBANG, U+2E18 ⸘ INVERTED INTERROBANG.

Predecessors of emoticons and emojis

The six additional punctuation marks proposed in 1966 by the French author Hervé Bazin in his book Plumons l'Oiseau ("Let's pluck the bird", 1966)^[28] could be seen as predecessors of emoticons and emojis.

These were:^[29]

• the "irony point" or "irony mark" (point d'ironie: )
• the "love point" (point d'amour: )
• 

  A point d'amour mark, or "love point"
  the "conviction point" (point de conviction: )
• the "authority point" (point d'autorité: )
• the "acclamation point" (point d'acclamation: )
• the "doubt point" (point de doute: )

"Question comma", "exclamation comma"

An exclamation comma

An international patent application was filed, and published in 1992 under World Intellectual Property Organization (WIPO) number WO9219458,^[30] for two new punctuation marks: the "question comma" and the "exclamation comma". The question comma has a comma instead of the dot at the bottom of a question mark, while the exclamation comma has a comma in place of the point at the bottom of an exclamation mark. These were intended for use as question and exclamation marks within a sentence, a function for which normal question and exclamation marks can also be used, but which may be considered obsolescent. The patent application entered into the national phase only in Canada. It was advertised as lapsing in Australia on 27 January 1994^[31] and in Canada on 6 November 1995.^[32]

Others

Other proposed punctuation marks include:^[33]

• Snark mark, indicating an ironic statement by putting a tilde next to terminal punctuation: .~ for dry sarcasm, !~ for enthusiastic sarcasm, and ?~ for sarcastic questions
• Rhetorical question mark:
• SarcMark for sarcasm