This document discusses research questionnaires. It begins by defining a questionnaire as a list of printed questions completed by respondents. The primary purpose of a questionnaire is to extract data from respondents in a standardized way. There are two main types of questionnaires: unstructured/open-form questionnaires that allow free responses; and structured/closed-form questionnaires that have predetermined answer choices. The document then provides details on the characteristics, advantages, and types of both questionnaire formats.