Condensed Matter is the branch of physics that studies the properties of matter under extreme conditions, such as high pressure and low temperatures. It is a relatively new field, which emerged in the early 20th century with the discovery of superconductivity and the development of quantum mechanics.
The study of condensed matter physics is essential for understanding the behavior of materials at both the microscopic and macroscopic level. For example, semiconductor devices are made possible by our understanding of how electrons interact with one another in solids. Likewise, advances in nanotechnology require an intimate knowledge of how atoms and molecules behave when they are confined to very small spaces.
Condensed matter physics also plays an important role in astrophysics and cosmology. The structure and evolution of stars and planets are determined by the interactions between their constituent particles, which can be studied using principles from condensed matter physics. In addition, many phenomena in the early universe, such as inflation and dark energy, can be better understood by studying how matter behaves under extreme conditions similar to those found in laboratories on Earth.