This document discusses the design and use of questionnaires. It defines a questionnaire as a set of questions used to gather information from individuals. Questionnaires can be administered via mail, phone, interviews, as handouts, or electronically. There are two main types of questions: open-ended questions that allow free responses and closed questions like multiple choice. Proper construction and administration are important to get useful statistical information. Factors like question wording, order, and avoiding sensitive topics should be considered when designing a questionnaire.