People use the term “hot rod” loosely; even today, there's no more agreement on where the term comes from than there is on what is or isn't a hot rod.
This quick overview of core styles, from the Hot Rod Philippine Club, will give you some context for the week's discussion. They leave out some of the odder, more interesting trends in hot rods, such as 70s obsession with hot rodding vans, and have little to say about the kids these days, but their definitions and examples are a good grounding for further exploration.
Tomorrow? We're getting loud and dirty.