Proteomics is the large-scale study of proteins, particularly their structures and functions. Proteins are vital in living organisms, as they are the main components of the physiological pathways of cells. The term "proteomics" was coined to make an analogy with genomics, the study of the genes. The proteome of an organism is the set of proteins produced by it during its life, and its genome is its set of genes. The proteome of a cell under a particular stimulation is the set of proteins in it. The word "proteome" derives from "proteins" and "genome", since the genome encodes proteins. Proteomics is often considered the next step in the study of biological systems, after genomics. It is much more complicated than genomics, mostly because while an organism's genome is rather constant, a proteome differs from cell to cell and constantly changes through its biochemical interactions with the genome and the environment. One organism has radically different protein expression in different parts of its body, different stages of its life cycle and different environmental conditions. Another major difficulty is the complexity of proteins relative to nucleic acids. This journal presents the latest research in the field.