ABSTRACT
Phase transition is ubiquitous in nature. It is manifested in a large, experimentally detectable change in thermodynamic functions like entropy, enthalpy and/or specific heat of a system that occurs due to infinitesimal change in a control parameter like temperature, pressure, etc. The subject of phase transition is of great importance in most branches of natural and biological sciences and acts as a unifying force across disciplines. Actually, it is a discipline by itself in its own merit, with entire books devoted to the subject [1,2]. There are diverse types of phase transitions that we encounter in nature and yet there is an amazing unity among such diversity. While a system may exhibit anomalous behavior near a phase transition, a unifying property among all different kinds of phase transition is the nature of discontinuity or divergence of thermodynamic functions at the point of phase transition. Depending on such properties, a phase transition is categorized into a different order, namely first order, second order, etc. This classification helps in grouping of phenomena of similar characteristics together. In this chapter we discuss a few from the large number of phase transitions observed in nature and also present the elementary concepts that are used to understand phase transitions.
