Date: 2016mar15 Keywords: frecent, freecent, frecency, recent, frequent Q. What's a good way to decide what to cache? A. You can use frecency. Frecency is any heuristic that combines the frequency and recency into a single measure. https://en.wikipedia.org/wiki/Frecency The Facebook newsfeed probably uses frecency to decide what to show too. - Newer thing are favoured (recent) - Things with lots of views/likes do well (that's the frequent)