What is a short sequence of keyboard letters and symbols usually emulating a facial expression which shows a feeling that adds to the meaning of a message?

A short sequence of keyboard letters and symbols that emulates a facial expression is called an "emoticon." Emoticons, such as :) for a smile or :( for a frown, convey emotions and enhance the meaning of text-based communication. They help convey tone, sentiment, and context in written messages, enriching the interaction between the sender and recipient.