The photosynthetic activity of far-red photons was discovered 70 years ago, but has largely been ignored since then. Recent research has drawn new attention to the importance of far-red photons. This short presentation will cover the history of research on photosynthetic responses to light spectrum, recent work on the importance of far-red photons, and a discussion of the implication of (not) extending the definition of PAR. There will be ample time for discussion following the presentation.