This practical introduction to the field focuses on the design, architecture, and operation of technologies based on organic compounds and conjugating molecules. It shows the reader how material structure relates to semiconducting properties, and then explores in detail the electronic devices that harness their unique properties. The author also extends the discussion to printed electronics, covering large-area, low-cost film deposition, patterning, processing, and encapsulation. The reader will gain a deep understanding of how the devices work and how the applications are designed and operate.