Research can be classified into different categories depending on the perspective under which the research activity is initiated and conducted. There are mainly three perspectives in categorizing research, namely application of research study, objectives in undertaking research, and inquiry mode employed for research.

Based on its application, research can be categorized into pure/basic/fundamental research and applied/decisional research. Pure/basic/fundamental research is conducted to look into some aspects of a problem or an issue for the first time. It involves developing and testing theories and hypotheses that are intellectually challenging to the researcher, but may or may not have practical application. This research type is to add to the existing body of research method and to the advance of knowledge. On the other hand, applied/decisional research is done to solve specific, practical questions or problems such as policy formulation, administration and understanding of a phenomenon. This type of research is usually either exploratory or descriptive.

Based on its objective, research is classified into descriptive, correlational, explanatory, and exploratory research. Descriptive research attempts to explain a situation, problem, phenomenon, service or program or provides information including the living conditions of a community, or describes attitudes towards an issue; which makes this research conclusive in nature rather than inquisitive. Commonly, this type of research is used to answer questions of who, what, when, where, and how associated with a particular problem. The main point is that descriptive research is to observe and describe a research subject or problem without influencing or manipulating variables in any way. Correlational research measures two (or more) variables, understands, and assesses the statistical relationship between them with no influence from any extraneous variables. It is basically looking for variables that seem to interact with each other so that when one of the variables (independent variable) changes, the other variable (dependent variable) will also change. Explanatory research aims to explain why events occur, to build, elaborate, extend or test a theory. An explanatory survey may look into factors contributing to something, or seek to model the variables. Exploratory research is conducted to find a solution for a problem that has not been studied more clearly. Usually, this research is trying to answer questions like what, why, and how.

Based on its inquiry mode, research is classified into structured approach and unstructured approach. Structured approach to inquiry is usually classified as quantitative research where the process, objectives, design, sample, and questions to ask are all pre-determined. It is more appropriate for determining the extent of a problem, issue, or phenomenon. Unstructured approach to inquiry is usually classified as qualitative research where the problem, issue, or phenomenon needs to be explored. There are also possibilities in which a researcher combines quantitative and qualitative approaches to answer the research questions.

Other types of research are conceptual and empirical research. Conceptual research is associated with some theoretical ideas or presuppositions and is generally used to develop new concepts or to get a better understanding of an existing concept in practice. By contrast, empirical research draws together the data based on experience of observation alone, often without due regard for system and theory. It is data-based research, coming up with conclusions which are capable of being verified by observation or experiment.