 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 ( illustration right ) . 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 ( illustration below ) . 
 Shortly after the invention of movable type , highly variable spacing was created <a href='null_relcl' title='1'><mark>that</mark></a>could create spaces of any size , and allowed for perfectly even justification . Early American , English , and other European typesetters <a href='null_genetive' title='2'><mark>'</mark></a>style guides ( also known as printers <a href='null_genetive' title='3'><mark>'</mark></a>rules ) specified spacing standards <a href='null_relcl' title='4'><mark>that</mark></a><a href='uninflect' title='5'><mark>were</mark></a> 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 ( illustration right ) . The relative size of the sentence spacing would vary depending on the size of the word spaces and the justification <a href='uninflect' title='6'><mark>needs</mark></a> . For most countries , this remained the standard for published work until the 20th century . Yet , even in this period , <a href='dey_it' title='7'><mark>there</mark></a> <a href='uninflect' title='8'><mark>were</mark></a> publishing houses ( notably in France ) <a href='null_relcl' title='9'><mark>that</mark></a>used a standard word space between sentences — a technique called French spacing ( illustration below ) . 
Shortly after the invention of movable type , highly variable spacing was created could create spaces of any size , and allowed fa perfectly even justification . Early American , English , and other European typesetters  style guides ( also known as printers  rules ) specified spacing standards was 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 b em @-@ spaced , and that words should bb1 / 3 or 1 / 2 em @-@ spaced ( illustration ryte ) . The relative size of the sentence spacing would vary depending on da size of the word spaces and the justification need . Ffamost countries , dis remained tdastandard fofirublished work till thda0th century . Yet , even in this period , it was publishing houses ( notably in France ) used a standard word space between sentences — a technique called French spacing ( illustration below ) .