What is a Vaal run?

Newb question - I have seen a number of farming posts discussing 'vaal runs' - are those runs through the vaal ruins, or runs through the waterfall/vaal temple up to the boss at the top of the pyramid?

People using the term are most likely referring to one person running through the pyramid to get to the boss as fast as possible (and doing it over and over)

But it was mostly a pre-0.10.2 thing, when you could turn in sets of lowbie unindentified rare items to get chaos orbs (and kill "Normal Vaal" in absolutely full rarity gear to get a high enough amount of rares per kill)

Thanks!