There's a book called The 4th Turning is Here, for a full explanation, read that. Put simply, there is a thing called a saeculum, meaning, the length of a good human life. During that "life" there are 4 generational shifts. You can obviously be born at any time during that period, and thus, putting you into a certain generation, of that time. The Fourth Turning Is the last generation/bit of time before the whole process starts again. During the 4th turning, there is a massive upheaval in society, then things come to a head (Pretty much like they are now) and then everything resets, back to the first turning. It's not an exact science as some saeculums can last longer than others. This one is set to peak/reset some time towards the end of this decade. Could be next year, could be 2033, we'll just have to see, but we're very much, currently living through it.