Strong coupling (SC) between light and matter has emerged in the last decade as a promising tool to control room-temperature photophysical processes in organic molecules. In this article, we aim to provide a pedagogical introduction to the various flavors of molecular SC involving (a) a single molecule in an optical nanocavity (e.g. a plasmonic junction), and (b) many molecules in an optical microcavity (the collective regime). Although the linear optical properties of these two systems are very similar, their chemical dynamics are drastically different from each another. We will highlight the relevant timescales and rates that can be manipulated via both flavors of SC. We will illustrate these ideas with theoretical and experimental examples from our previous work, which will help us distill the physical mechanisms that are at play in each SC case.