Just like we all know sexting is good for our relationships (as long as we keep these rules in mind), we know that responding to a text—any text—with "K." is not. It's much easier to be aggressive over text because you're not face-to-face with the person you're talking to, and people are finding new ways to express that aggression via the humble period. A new study by researchers at American University on text messages and IMs shows that the way we use punctuation has changed in order to convey new meaning through mediums that make it difficult to express tone, The New Republic reports.

Before texts, every sentence ended with a period. But with the advent of impersonal electronic communication, line breaks became a quicker and easier way to express the end of a thought. "The default is to end just by stopping, with no punctuation mark at all," Mark Liberman, a professor of linguistics at the University of Pennsylvania​, told The New Republic. "In that situation, choosing to add a period also adds meaning because the reader(s) need to figure out why you did it. And what they infer, plausibly enough, is something like, 'This is final, this is the end of the discussion or at least the end of what I have to contribute to it.'" In other words, because the period is a deliberate choice, including it is especially passive-aggressive.

Researchers drew their data from 22 college-age women attending a "large mid-western university" who recorded all the texts they sent and received over a period of 24 hours; they then turned in the data to be analyzed by researchers. Three men also completed the task, but for some reason (probably because the sample size was too small), their exchanges weren't analyzed. So the next time your girlfriend or BFF sends "That's great." instead of "That's great!" or a simple "That's great," you know that, whatever it is, it's definitely not great.