I was taught, as I am sure many of you were, to put two spaces after any punctuation mark. This rule arose during the days of manual typewriter. But in our digital age, this two-space rule is outdated and unnecessary. In fact, now such authoritative sources as the Modern Language Association (MLA) recommends against it. So stop putting two-spaces after your periods and free up some room in your grants.
Personal note: This is a freakin' hard habit to break! Three years after hearing about this "change", I still regularly type two-spaces.