The ever-growing demands in energy production requirements necessitate the advancement of high-performance energy storage devices. In specific, supercapacitors have emerged as a prominent focus for their rapid energy storage and delivery, and long cycle life. The swift charge capabilities of supercapacitors render them suitable for diverse applications including transportation, wearable and flexible electronic devices, and numerous other sectors. They deliver energy density of higher magnitude than conventional capacitors and higher power densities than batteries. Notwithstanding their inherent advantages, the primary bottleneck in supercapacitor development is achieving high energy density. Energy density can be enhanced through either developing an advanced electrode material or elevating the cell voltage. To surmount these challenges, researchers are actively engaged in exploring novel electrode materials, finding the best electrolytes and in modifications of current collectors and separators. This chapter provides fundamental insights and highlights key factors that influence electrochemical performance. Further, it explores their historical development, energy storage mechanisms, diverse electrode and electrolyte materials, current collector options, cell design approaches and outlines metrics for evaluating their performance.