Nursing theory is defined as a creative and rigorous structuring of ideas that project a tentative, purposeful, and systematic view of phenomena". Through systematic inquiry, whether in nursing research or practice, nurses are able to develop knowledge relevant to improving the care of patients. Theory refers to a coherent group of general propositions used as principles of explanation. In the early part of nursing's history, there was little formal nursing knowledge. As nursing education developed, the need to categorize knowledge led to development of nursing theory to help nurses evaluate increasingly complex client care situations. Nursing theories give a plan for reflection in which to examine a certain direction in where the plan needs to head. As new situations are encountered, this framework provides an arrangement for management, investigation and decision-making. Nursing theories also administer a structure for communicating with other nurses and with other representatives and members of the health care team. Nursing theories assist the development of nursing in formulating beliefs, values and goals. They help to define the different contribution of nursing with the care of clients. Nursing theory guides research and practice.