Proteomics is one of the most potent methods in biomedical research, which enables identification and comprehensive characterization of cellular targets and understanding the mechanisms of actions for therapeutic agents and the main functional constituents of biochemical schemes, specifically biomarkers. Diagnostic markers are the main cellular or molecular events that link a specific environmental exposure to a health outcome. Diagnostic markers show associations between exposure to environmental compounds, diagnosis of subgroups that are at increased risk for disease and development of chronic diseases. Rapid detection and treatment serves as a strong tool to prevent and control progression of infectious diseases. A panel of biomarkers can be made into commercial diagnostic kits which could offer precision and economic advantages. Hence, there is a great need for diagnostic markers that could be used in the development of diagnostic kits and microfluidic technologies. This bookprovides an overview of the most commonly used techniques in biomarker discovery.