The document discusses the meaning, purpose, advantages, and disadvantages of a questionnaire. A questionnaire is a research instrument with predefined written questions to obtain specific information from respondents. It was invented by Sir Francis Galton and consists of questions tailored to the research purpose. Questionnaires allow researchers to efficiently collect large-scale, standardized data to minimize bias and analyze scientifically, but they risk dishonest responses and cannot capture additional respondent insights beyond the predefined questions.