This chapter discusses protein, explains its significance and describes the role of protein in cell signaling. It considers the structural and functional attributes of protein and explains the process of protein biosynthesis and outlines different methods of protein prediction models. The chapter examines the significance of protein folding and protein modification. It provides protein transport and degradation and presents genetic regulation of protein synthesis. The chapter also discusses tools and techniques used to analyze proteins. Listing all the protein modifications that might be studied in a “proteomics” project would require a discussion of most of biochemistry. One of the interesting features of proteomics is that it gives a much better understanding of an organism than genomics. Native polyacrylamide gel electrophoresis (PAGE) is an electrophoretic separation method typically used in proteomics and metallomics. Sodium dodecyl sulfate-PAGE is a technique widely used in biochemistry, forensics, genetics, and molecular biology to separate proteins according to their electrophoretic mobility.