This is the No. 1 mistake people make when texting, etiquette expert says

The number one mistake people make when texting according to etiquette experts is the misuse of punctuation, specifically periods. Daniel Post Senning, co-author of "Emily Post's Etiquette: The Centennial Edition," states that periods can alter the tone of a text12. For example, the difference between someone saying, 'Funny!' and 'Funny.' is dramatic in terms of how it's interpreted. Periods can add a tone of hostility to short messages, and it is not necessary to end "one or two-word replies" with a period.

The use of periods in text messages can alter the perceived tone of the communication by making the message appear more passive-aggressive, insincere, or even hostile. This is because, in the context of text messaging, using a period at the end of a sentence is considered overly formal and can signal a definitive stop, as if to say "This is final, this is the end of the discussion1." As a result, text messages ending with a period may be perceived as less friendly or more distant compared to those without a period.

Etiquette expert Daniel Post Senning suggests that periods can add a tone of hostility to short messages and advises against using them in one or two-word replies. Instead, he recommends reserving periods for instances where a serious tone is truly intended. On the other hand, exclamation points can be used more freely in text messages to show enthusiasm and modify the tone in a positive way.