Organic electronics is an emerging field that utilizes π-conjugated organic materials, including small molecules and polymers, to develop lightweight, flexible, and environmentally sustainable electronic devices. Although conventional silicon-based electronics continue to dominate high-performance applications due to their superior charge carrier mobility, organic semiconductors offer unique advantages such as mechanical flexibility, low-temperature processing, tunable electronic properties, and compatibility with biological systems. This thesis presents a comprehensive review of the fundamental principles, device architectures, fabrication techniques, characterization methods, and future prospects of organic electronics. The study focuses on four key device categories: Organic Field-Effect Transistors (OFETs), Organic Photovoltaics (OPVs), Organic Light-Emitting Diodes (OLEDs), and Organic Electrochemical Transistors (OECTs).