A "nursing theory" is a description or explanation of an area of professional nursing. This description or explanation is proposed in a systematic way in order to provide the broadest and most practical information for use in nursing practice and research. However, there is no one "universal" nursing theory. There are three major types of nursing theories, dealing with general concepts and models for everyday experiences. The greatest barrier to effective application of any nursing theory is trying to employ the wrong type of theory, or model, in a particular nursing situation.