While a period ends a sentence, a comma indicates a smaller break. Some writers think of a comma as a soft pause—a punctuation mark that separates words, clauses, or ideas within a sentence.
An interjection is a word or expression that occurs as an utterance on its own and expresses a spontaneous feeling or reaction.
It is a diverse category, encompassing many different parts of speech, such as exclamations, curses, greetings, response particles, hesitation markers, and other words.