How is the compatibility of modules in Bitrix arranged?

Question

1C-Bitrix

We have made a module for Bitrix version 18.5 and we are thinking how it will work on other versions. Can anyone suggest which version and how it will behave?
Another question of interest is - which version of Bitrix is ​​most often used?
Maybe someone knows the statistics, like:
1. 18.5
2. 16
3. 17
...
10. 8
?
Thank you!

Answer 1

It makes no sense to make a module for an outdated version of Bitrix. The implementation model in Bitrix goes through the marketplace, which is accessed by customers with an active license, most of which will have the latest updates.

Answer 2

We have made a module for Bitrix version 18.5 and we are thinking how it will work on other versions. Can anyone suggest which version and how it will behave?
No one can say this except you. You need to know what features of 18.5 you used. If you used the documented API, did not use direct access to the database, then the module will most likely work on all subsequent versions. The Bitrix API is very stable. On previous versions, it will or will not work depending on which API features you use and in which version they first appeared.
PS
If you want frankly - I would not use the module from the developer who asks such a question at all. Sorry.