And the methods used to apply knowledge can be differed according to the convenience and particularity of the situations. Nursing is both a profession and a discipline nursing as field profession is a practice and when we consider it as knowledge it is a discipline. There are a number of theories advocated by scientists. Theories are definitely the backbone of any discipline and nursing is no exception here. Here I would like to make a brief explanation on the components of theory. Theory consists concepts that are inevitable for practice guidance. Nursing theories are formed out of concepts, definitions assumptions with or without the help of other disciplines or derived from different particular instances; and there are a number of inter- relationships made between them for predicting, explaining and prescribing things (Nursing Theories: An Overview). Theories universally contain concepts, prepositions, metaparadigm, philosophies and conceptual models. Concepts are occurred in mind as ideas on a phenomenon. This is an intellectual process through intuition. They indicate and signify ideas observations or experiences. For instance, relief can be an idea in nursing. Concepts can be useful in creating knowledge on phenomena. These concepts also are supported by constructs. Generally concepts are of three kinds; empirical, inferential and abstract. A statement of relationship between two concepts are said to be prepositions. Structural holarchy of contemporary nursing knowledge include components like metaparadigm, conceptual models, theories, and empirical indicators and their level of abstraction differs; and concepts and propositions are the important to explain a theory (Lesson, 2.1) There are several theories of nursing used by the practitioners today; and those theories are grouped into divisions according to the nature and functions of the theory. Nursing theories can be classified from different categories. Depending on its function it can be divided into four namely, descriptic, explanatory, predictive and perspective. Based on generalisability of their principles they are divided into Meta theory and grand theory. Middle range theory and practice theory are the third one based on the principles of the discipline. Looking from the stand point of philosophy, it can be needs theories, interaction theories, outcome theories and humanistic theories. But the important classification is into grand theories and middle range theories. Prominent among the theories today are Orland nursing theory, Newman theory, Parse theory, Peplaun Theory and Watson Theory. There are also theories called borrowed, which are adopted from other disciplines. Grand theories are the most abstract in nature. Grand theories are instrumental in making nursing as a science. Grand theories are built up on concepts and propositions that are less abstract. These theories are difficult to be practiced in daily nursing tasks. On the other hand middle range theory is more concrete. Middle range theories are originated from conceptual models directly. So, they are very much useful in current nursing practice. Middle range theories are of high middle level, middle- middle level and low middle level. 2. The meaning of metaparadigm of nursing? A metaparadigm is considered to be the way to describe concepts that concern any profession or domain. This concept was firstly introduced in early 1970’s.