This document discusses different types of modality words - modal verbs, nouns, and adverbs. It provides examples of each and explains how they are used to express degrees of certainty, obligation, possibility and other modal meanings. Modal verbs are auxiliary verbs that modify the meaning of the main verb. Modal nouns are names of qualities or states that express modality similar to modal verbs. Modal adverbs also express modality and describe verbs, adjectives or other adverbs. The document aims to distinguish these three types of modality words and how they are used in sentences.