From humble beginnings, diode laser technology has evolved to become an invaluable tool for many aspects of our daily lives. Diode lasers exhibit a number of favorable properties which have led to their wide adoption, including compactness, robustness, and mass producibility. Just as important is the ability to engineer the emission wavelength and performance to be suitable for an application of interest. However, accomplishing this often requires significant innovation. A principal illustration of this was the development of 1.3 and 1.55 micron wavelength lasers for telecommunication, which required innovations in InP-based Quantum physics, atomic engineering, and material growth. Other examples include Al-free near infrared lasers for high efficiency solid state laser pumping and the III-Nitride materials for blue/violet laser diodes.