I know it’s a tiny thing, and based on the number of times it crops up in manuscripts I receive, I imagine I’m one of the very few to notice it, but the comma or period after an italicized word should not, as a rule, be italicized, because yes, there is a difference. Similarly, neither should the space (again, there actually is a difference between an italicized space and a non-italicized space), nor, for that matter, any other punctuation mark. So why do some word processing programs seem to want to include the following space or punctuation mark when italicizing the word?

And a slightly bigger part of it: the possessive of an italicized proper noun shouldn’t be italicized (for example, when talking about the USS Enterprise’s anchor chain).