High harmonic generation (HHG) is a unique quantum light source with fundamentally new capabilities – producing ultrafast, laser-like, beams with linear or circular polarization throughout the extreme ultraviolet (EUV) and soft X-ray region, all on a tabletop. This talk will introduce and review recent developments in HHG sources, as well as exciting advances in spectroscopy of materials. A host of applications in materials and nano science have now been demonstrated, including how to engineer energy flow in nanostructures and interfaces, measuring how fast a material can change its electronic or magnetic state, and directly visualizing the dynamic band structure of material and electron-electron interactions on femtosecond and even sub-femtosecond timescales. For quantum materials, a new technique called ultrafast electron calorimetry makes it possible to identify hidden phases in materials that traditional spectroscopies are blind to. Finally, the high spatial coherence of high harmonic sources makes it possible to implement wavelength-limited imaging in the EUV and soft X-ray regions for the first time.