The nodejs async module: https://github.com/caolan/async provides 2 similar methods, async.waterfall and async.series.
What is the difference between them?
It appears that async.waterfall allows each function to pass its results on to the next function, while async.series passes all results to the final callback. At a higher level, async.waterfall would be for a data pipeline ("given 2, multiply it by 3, add 2, and divide by 17"), while async.series would be for discrete tasks that must be performed in order, but are otherwise separate.