1. Introduction. Whenever a researcher is conducting a study, they would think about what is the research question , the methodology ,the data needed , the instrument for the data collection, and data analyze. Before the researchers decide which would be the most appropriate methods for their research, they need to find out a little more about these methodologies weather, its qualitative or quantitative research method and tools or instruments that need to be used in the research. there are several research methods and instruments, for example questionnaires, interview, focus group, and observation..etc. Some of these instruments are for qualitative research design and some others are quantitative research design. This has a description of the purpose of the study as well as the organization(s) involved. The respondent is assured of anonymity / confidentiality of information volunteered, making clear that there are no wrong or right answers. Honest answers are also requested. The instruments to be used have to be well identified. Several considerations have to be made before designing the questions. These considerations are discussed below. Questionnaires are very important data collection instrument for most researchers, know the exact way how to use it , not conducting the proper questionnaires type could be misleading, and could lead to a confusion on what kind of data needed or questions asked. In the following research paper, the researcher will try to answer the questions asked about questionnaires, kinds of questionnaires, how, and when to use them, the advantages and disadvantages of questionnaires. 1.1 Purpose of the research. This research paper is identify questionnaires as a research instrument, and classify the types of the instrument, when to use questionnaires, how to conduct the questionnaires, And how to analyze the questionnaires data . The advantages and disadvantages of questionnaires. It is an attempt to answer most common questions about questionnaires.1.2 Background information about questionnaires.The questionnaire may be a qualitative research method or a quantitative research method depending on the type of questionnaires that is been used ,posted or presented in an interview format. A questionnaire may include attitude scales, check lists, projective techniques, ranking scales and a variety of other research methods. As an essential research instrument and a device for data collection, a questionnaire has its main function as measurement (Oppenheim 100). It is the main data collection method in surveys and yield to quantitative data. Also, due to provision for open ended questionnaires , the instrument may be used to generate qualitative and exploratory or analytical data for the use for the social studies . The nature of the population to be surveyed is the major concern .And the mount of arrangements depends on several effects. The kind of survey could be factual or analytical. (Dornyei 101)2. Definition of questionnaires . Iitems can be both, qualitative and quantitative method depending the nature of questionnaire. Particularly, quantitative methods data collection, by using answers through closed-ended items with multiple choice options, the data obtained may involve pie-charts, bar-charts and/or percentages. Qualitative research data Answers and analyzed are obtained from open-ended questionnaire items, and they involve discussions and critical analyses without usage of numbers and calculations. For a standard 1o,000-15,000 word business dissertation, including 15-25 questions in questionnaires will usually be sufficient. Questions need be formulated in an unambiguous, explicit and straightforward manner and they should be presented in a systematic order.