What does Microsoft do with the activity history?

Question

I just turned on 'send my activity history to Microsoft' to use the 30 day timeline feature, I'm surprised to find that all of my actions from the last 30 days popped up in the timeline instantly, doesn't this mean that my activity history is stored anyways and Microsoft is just forcing me to login to access the full activity history of the last 30 days? Also is this activity history sent to Microsoft? ( I mean the history from the last 30 days, since I only turned it on today ). 

I also want some information on what the data is used for because I had read a few Microsoft and third party articles about privacy and activity history but none gives a proper explanation about it.

Answer 1

The data is used to diagnose problems with Windows and improve its performance. No personal information is transmitted.

The way Microsoft - and Google, Facebook, Apple, Twitter, etc. - learns about you is through the web browser.