What are dipped headlights and when should you use them?

Having dipped headlights on your car is the intermediate step between sidelights and main beam headlights. New cars will generally also have running lights, but these work autonomously and don't require any input from the driver, so even if your lights are off, they are on - if you know what we mean.
To change between off (or daytime running lights only), side lights, dipped beam and main beam, manual input from the driver is required, usually in the shape of a twisted indicator stalk or tu