"Hiiiii," he texted. “Hiiiii,” I responded. “How are youuuuu?”

Rest assured: I am an adult. I even write for a living—often about grammar, punctuation, and how we use words in these tech-enhanced times.

My phone buzzed again. “Fiiiiiine,” he replied. Almost involuntarily, I responded: “What are you doooooing? I misssss youuuuu!”

Evvvvverywherrrre, from instant messages to texts to tweets and even e‑mails, I see examples of what language watchers call “word lengthening.” The habit began among teens and 20-somethings, but it is no longer limited to them. Adults are adding o’s to their no’s, s’s to their yes’es, and i’s to their hi’s, to say nothing of a glut of exclamation points. In response to some recent news, my 60-something mom wrote, “LOVE IT AND YOU TOO!!!!” What is going on?

For the past five years, Sali Tagliamonte, a linguist at the University of Toronto, has been gathering digital-communications data from students. In analyzing nearly 4 million words, she’s found some interesting patterns. “This reduplication of letters, it’s not all crazy,” she told me. Certain vowels—o, a, and e—are the most-frequent candidates for multiplication. Words are most frequently elongated by two or three letters at a time. Elongations are common in instant messaging and texting, but less frequent in e-mail. And as with other linguistic trends—Tagliamonte mentioned the use of like for quotation and so for intensification (“I was like, ‘That’s so funny!’ ”)—“women are at the forefront.”