This states that S.E. is a data processor and customers are the data controller . However after we enter data it is S.E. which determines how it is shown and/or delivered (i) to their servers . So shouldn't S.E. be the data controller in this regard? And here for integration with M.S. Teams S.E. states it is a joint controller with the customers . Like how is this determined? Have posted several downvoted questions on GDPR.GOOGLE states that GOOGLE is the data controller and app developers are joint controllers. So again, Like how is this determined? On top of that does the responsibility according to GDPR for the data collected by one joint (b) controller also shared with controller (a) who is the other controller?. Then have seen several sites where it just seems one controller has just linked to the other controller ( who claims to be responsible under the GDPR ) and has basically left all responsibility to them . Obviously it is not possible to ensure compliance of third parties . However if one uses some uses GitHub Pages to host a website or use AdMob in one's app one must receive GDPR requests and probably forward them to GOOGLE or Github somehow but the developer cannot ensure they comply.Also how will the developer keep consent records? Everyone does not capital at beginning to host a server and if one does one mst obey more laws! **EVERYTHING JUST SEEMS TO CONTRADICT!!**So can one explain this confusion. Have tried to do make the wording of this question as good as possible .
StackExchange is a processor under GDPR because it processes the data you provide it when you sign up and input personal information.
It's determined by an analysis of what function(s) the business is performing. If you are merely processing the data but don't have control over it (e.g. another business is using your software to do something with data that it is providing you) then you are likely to be a data processor.
Conversely, if you control the data, you are likely to be a data controller.
It is possible to be both a data controller and a data processor at the same time.
That specific link in your post goes on to state:
Our business customers may qualify as controllers when they purchase certain of our products and services. We act as processors on behalf of such Customers.
This is referring to the Teams product that StackExchange offers or whatever the "internal company-only question and answer site" product they offer is called.