The document defines a questionnaire as a list of written questions related to a topic that is distributed to respondents to answer. It provides advantages such as being easy to construct and distribute, responses are easy to tabulate, and respondents can answer freely and accurately. Disadvantages include some respondents not being able to read or write, or not returning the questionnaire. The document outlines steps for constructing a questionnaire, including researching the topic, drafting questions, editing, pretesting, and finalizing the questionnaire. It also describes different types of questionnaire questions.