What's going on with Angular versions?

Question

Angular

Tell me in simple Russian words what is happening with the versions of Angular.
https://github.com/angular/angular/blob/master/CHA... I
slept calmly knowing that there was version 1, then version 2 came to replace it. And then I learn about the 4th version from various sources.
Where can I read what is the difference between 2 and 4 and where are the docks for the 4th version in general.
UPD: And here they are already writing about v5
https://pbs.twimg.com/media/C5tCM43VUAAwoKd.jpg:large

Answer 1

docks for version 4