Recently, while listening to contemporary and pop music, I discovered that many song uses an I - V - i or i - V - I modulation. For example, C major to G major to C minor. I want to know whether there is a name for this particular modulation technique?
I would call it a parallel modulation, since you're modulating to a parallel key. Googling for that term confirmed that this is what they are called, and led me to this video:
Hardly a modulation, as it goes to major on the last bar, but a piece that's in minor for its entirety but finishes with a tonic major. That's called a Tierce de Picardie. The 'Picardy third'. In the dim and distant past, a lot of serious music used this as an ending, somewhat brightening things up.
Going from major to minor is, I think a lot less common.A couple of examples would be nice.