The quantum field theory (QFT) is a universal common language of the condensed matter community. As any live language it keeps evolving and changing. The change comes as a response to new problems and developments, trends from other branches of physics and from internal pressure to optimize its own vocabulary to make it more flexible and powerful. There are a number of excellent books which document this evolution and give snapshots of “modern” QFT in condensed matter theory for almost half a century. In the beginning QFT was developed in the second quantization operator language. It brought such monumental books as Kadanoff and Baym [1], Abrikosov, Gor'kov and Dzyaloshinski (AGD) [2], Fetter and Walecka [3] and Mahan [4]. The advent of renormalization group and Grassmann integrals stimulated development of functional methods of QFT. They were reflected in the next generation of books such as Itzykson and Zuber [5], Negele and Orland [6] and Fradkin [7]. The latest generation, e.g. Tsvelik [8], Altland and Simons [9], and Nagaosa [10], is not only fully based on functional methods, but also deeply incorporates ideas of symmetry based on universality, geometry and topology. (I do not mention here some excellent specialized texts devoted to applications of QFT in superconductivity, magnetism, phase transitions, mesoscopics, one-dimensional physics, etc.)