From the late nineteenth century critics have regularly labeled certain compositions as 'literature', but the criteria for the definition have not always been made explicit. Criteria, implicit and explicit, vary. In definition of literature it could be consider the three areas; function, form and content. With criteria of function, form and content, the modern reader/researcher may locate a composition on a spectrum from least to most self-conscious communication. An awareness of the relative place of communicated words lifts the issue of defining literature from a sterile debate to an act of engagement. The most important activity in receiving a work as literary, and in appreciating a literature, is focusing on Language and its maneuver as widely as possible both in literary and in non-literary writings. Formalism is the first school which regularly put focus on language and its structures of the literary work for distinguishing from non-literary ones. This paper trace the formalism methods for understanding the difference between literary text and non-literary and in the end come to exact definition of literature.