The conspicuous omission of the period in text messages and in instant messaging on social media, he says, is a product of the punctuation-free staccato sentences favored by millennials — and increasingly their elders — a trend fueled by the freewheeling style of Facebook, WhatsApp and Twitter

“We are at a momentous moment in the history of the full stop,” Professor Crystal, an honorary professor of linguistics at the University of Wales, Bangor, said in an interview after he expounded on his view recently at the Hay Festival in Wales…

Researchers at Binghamton University in New York and Rutgers University in New Jersey have also recently noted the period’s new semantic force

They asked 126 undergraduate students to review 16 exchanges, some in text messages, some in handwritten notes, that had one-word affirmative responses (Okay, Sure, Yeah, Yup) Some had periods, while others did not

Those text message with periods were rated as less sincere, the study found, whereas it made no difference in the notes penned by hand