The document discusses interjections, which are words that express strong feelings or emotions like surprise. Interjections are usually placed at the beginning of a sentence followed by a comma or exclamation point. Examples of interjections given include "Wow!", "Ouch!", and "Zap!". The document also notes that interjections with strong feelings use an exclamation point and can stand alone, while those with less feeling use a comma and begin the sentence.