Difference in NGINX versions?

Question

Nginx

Difference in NGINX versions?
What is the difference between Stable version and Mainline version?
Why are there versions that start with 1, so to speak, and what are the versions that start with 2?
How to choose your 1st and 2nd version?

Answer 1

How can I choose version 1 and 2?

Of course, if you don't know what to choose, then choose the latest stable version, in this case 1.18.0
NGINX release 1.6 and 1.7. Versioning Features