The document discusses the differences between expressing present and past habits. It notes that present habits are usually expressed using "usually" or "normally" with the present simple tense. Past habits can be expressed using the past simple tense or "used to" for repeated actions or states in the past. It provides examples of how to form questions and negatives using "used to." The document also distinguishes between "used to" for past habits and "be used to" or "get used to" which refer to being or becoming accustomed to something.