https://en.m.wikipedia.org/wiki/Fourth_Estate
Just like within actual government there’s supposed to be balance of power between different branches or houses, there’s this idea that the role of the press is to hold governments accountable.
(More of an ELI12, but that’s the gist of the idea)
I’m a fan of Botany in a Day. Rather than drilling down on all of the details of any particular species, the author covers the properties of a handful of families that make up almost everything we think of as plants. I.e. what is true of everything in the mint family, or the rose family.