The document discusses three main types of research design: exploratory research, descriptive research, and causal research. Exploratory research is conducted early in the research process to gain insights, generate hypotheses, and clarify concepts. It uses flexible and unstructured methods like literature reviews, focus groups, and case studies. Descriptive research describes the characteristics of a population using structured methods like longitudinal and cross-sectional studies. The goal is to provide associations between variables. Both exploratory and descriptive research differ from causal research, which aims to determine cause-and-effect relationships between variables.