This lecture introduces the theory of distributed circuits in electromagnetism, contrasting it with the traditional theory of localized circuits. The instructor explains the importance of considering time delays in circuits, especially at high frequencies, and how this theory is crucial for various applications such as communication networks, radar systems, and power distribution networks. The difference between localized and distributed circuits is illustrated through examples, emphasizing the need to account for time delays in distributed circuits. The lecture concludes by highlighting the significance of understanding when to apply localized circuit theory versus distributed circuit theory in practical engineering scenarios.