[jmb99]

This one is a bit more reasonable (to me at least). It seems to be an internet/texting convention that messages ending with a period are more formal/serious or potentially angry/irritated, whereas messages without a period are lighter/more fun. As an example:

“Have you taken the dog out?”

“Yes”

Vs

“Have you taken the dog out?”

“Yes.”

The second comes across as the responder being potentially irritated at the asker. I believe that this comes down to the amount of effort required to type the reply; adding a period is making the explicit choice to do so, whereas not doing so is the default. This isn’t the case for sentences in the middle of a multi-sentence answer, since a separator is needed anyways. But I find myself not adding a period even at the end of multi-sentence messages, and I automatically read any message ending with a period with a different tone than one which does not.

Maybe I’m just nuts though, that’s always an option. But with text being such a relatively limited medium for conveying emotion in short messages, I think this is a reasonable solution.