Have you ever read a message from a friend — or worse, a business document — that just didn't come across correctly? If there's a misplaced, misused, or just plain missing punctuation mark, it can change the entire makeup of a sentence and make the end result read totally different than intended. And it can be terribly embarrassing, to boot. Understanding the rules of punctuation and knowing how to use the various marks can save you from confusing your readers, whoever they may be. We've collected eight tools to keep on your iOS device to help ensure you properly use punctuation marks. National Punctuation Day was last week, so while this roundup may not be terribly punctual itself, there's never a bad time to bone up on your punctuation skills.