A theory is a group of related concepts that propose action that guide practice.

A nursing theory is a set of concepts, definitions, relationships, and assumptions or propositions derived from nursing models or from other disciplines and project a purposive, systematic view of phenomena by designing specific inter-relationships among concepts for the purposes of describing, explaining, predicting, and /or prescribing. The Neuman’s system model has two major components i. e. stress and reaction to stress.The client in the Neuman’s system model is viewed as an open system in which repeated cycles of input, process, out put and feed back constitute a dynamic organizational pattern.

The client may be an individual, a group, a family, a community or an aggregate. In the development towards growth and development open system continuously become more differentiated and elaborate or complex. As they become more complex, the internal conditions of regulation become more complex. Exchange with the environment are reciprocal, both the client and the environment may be affected either positively or negatively by the other.

The system may adjust to the environment to itself. The ideal is to achieve optimal stability. As an open system the client, the client system has propensity to seek or maintain a balance among the various factors, both with in and out side the system, that seek to disrupt it. Neuman seeks these forces as stressors and views them as capable of having either positive or negative effects.

Reaction to the stressors may be possible or actual with identifiable responses and symptom.