<P> Sentence spacing is the horizontal space between sentences in typeset text . It is a matter of typographical convention . Since the introduction of movable - type printing in Europe, various sentence spacing conventions have been used in languages with a Latin alphabet . These include a normal word space (as between the words in a sentence), a single enlarged space, and two full spaces . </P> <P> Until the 20th century, publishing houses and printers in many countries used additional space between sentences . There were exceptions to this traditional spacing method--some printers used spacing between sentences that was no wider than word spacing . This was French spacing--a term synonymous with single - space sentence spacing until the late 20th century . With the introduction of the typewriter in the late 19th century, typists used two spaces between sentences to mimic the style used by traditional typesetters . While wide sentence spacing was phased out in the printing industry in the mid-20th century, the practice continued on typewriters and later on computers . Perhaps because of this, many modern sources now incorrectly claim that wide spacing was created for the typewriter . </P> <P> The desired or correct sentence spacing is often debated but many sources now say additional space is not necessary or desirable . From around 1950, single sentence spacing became standard in books, magazines and newspapers, and the majority of style guides that use a Latin - derived alphabet as a language base now prescribe or recommend the use of a single space after the concluding punctuation of a sentence . However, some sources still state that additional spacing is correct or acceptable . The debate continues . Many people prefer double sentence spacing for informal use because that was how they were taught to type . There is a debate on which convention is more readable; the few recent direct studies conducted since 2002 have produced inconclusive results . </P> <P> Shortly after the invention of movable type, highly variable spacing was created that could create spaces of any size, and allowed for perfectly even justification . Early American, English, and other European typesetters' style guides (also known as printers' rules) specified spacing standards that were all essentially identical from the 18th century onwards . These guides--e.g., Jacobi in the UK (1890) and MacKellar, Harpel, and De Vinne (1866--1901) in the U.S.--indicated that sentences should be em - spaced, and that words should be 1 / 3 or 1 / 2 em - spaced . The relative size of the sentence spacing would vary depending on the size of the word spaces and the justification needs . For most countries, this remained the standard for published work until the 20th century . Yet, even in this period, there were publishing houses (notably in France) that used a standard word space between sentences--a technique called French spacing . </P>

When did 2 spaces after a period change