 <unk> advances began affecting sentence spacing methods . In 1941 , IBM introduced the Executive , a typewriter capable of proportional spacing — which had been used in professional typesetting for hundreds of years . This innovation broke the hold that the monospaced font had on the typewriter — reducing the severity of its mechanical limitations . By the 1960s , electronic <unk> systems ignored runs of white space in text . This was also true of the World Wide Web , as HTML normally ignores additional spacing , although in 2011 the CSS 2 @.@ 1 standard officially added an option that can preserve additional spaces . In the 1980s , desktop publishing software provided the average writer with more advanced formatting tools . By the late 20th century , literature on the written word had begun to adjust its guidance on sentence spacing . 
