Excuse me, could you please elaborate on the three fundamental categories of spectra in the realm of physics? I understand that spectra play a pivotal role in understanding various phenomena, but I'm curious to know the specific classifications that encompass their diversity. Are these types related to the nature of the radiation source, the manner in which light interacts with matter, or perhaps a combination of both? I'm eager to gain a clearer understanding of how these spectra differ from one another and the significance they hold in scientific inquiry.