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 (ouch!, wow!), curses (damn!), greetings, response particles, hesitation markers, and other words. Due to its diverse nature, the category of interjections partly overlaps with a few other categories like profanities, discourse markers, and fillers. The use and linguistic discussion of interjections can be traced historically through the Greek and Latin Modistae over many centuries.