This book offers a comprehensive exploration of operational amplifiers (op-amps) and their wide-ranging applications in both linear and non-linear circuits. It begins with a foundational introduction to op-amps, then progresses through linear applications before examining non-linear circuits. Key topics include waveform generators, active filters, and data converters. Later chapters delve into advanced analog and digital applications such as voltage regulators, analog multipliers/dividers, and the versatile 555 timer. The book also covers the implementation of logic gates, combinational circuits, and flip-flops using op-amps. Appendices provide practical insights through tutor kits developed by the author, making this an invaluable resource for students, educators, and professionals in electronics.