The proteome is defined as the total protein complement of a genome—whether that genome is associated with an individual cell, tissue, or organism (Wasinger et al., Electrophoresis 16:1090–1094, 1995). Proteomics refers to the application of technologies to characterize the proteome. The term “proteome” was coined by researchers at the University of Sydney, Australia, in a paper published in 1995 (Wasinger et al., Electrophoresis 16:1090–1094, 1995). But did proteomicsproteomics really begin in 1995 or were researchers doing proteomic research long before? As a PhD student, I would tell people that my field of expertise was protein science, as I was involved in determining the three-dimensional structures of proteins using nuclear magnetic resonance (NMR) spectroscopy. As my career evolved to using mass spectrometrymass spectrometry (MS) to analyze complex mixtures of proteins, my field of expertise was proteomics. While still studying proteins, what had changed was the number of proteins I was analyzing per experiment. In a nutshell, proteomics is simply the large-scale study of proteins. While protein scientists have been studying proteins for almost 200 years (Mulder, Bulletin des Sciences Physiques et Naturelles en Néerlande 104, 1838), proteomics has increased the throughput and the ability to characterize proteins in the context of other proteins within their environment. While well-known for its high-throughput ability to identify and quantitate proteins, proteomics encompasses several different facets of protein characterization including such things as structure, function, protein-protein interactionsprotein-protein interactions, posttranslational modificationspost-translational modifications, and protein quantitation. Data acquired under any of these broad categories can be applied to greater understand something part of the cell system.