Amazon keeps records of every motion detected by its Ring doorbells, as well as the exact time they are logged down to the millisecond.
The details were revealed via a data request submitted by the BBC.
It also disclosed that every interaction with Ring's app is also stored, including the model of phone or tablet and mobile network used.
One expert said it gave Amazon the potential for even broader insight into its customers' lives.
"What's most interesting is not just the data itself, but all the patterns and insights that can be learned from it," commented independent privacy expert Frederike Kaltheuner.
"Knowing when someone rings your door, how often, and for how long, can indicate when someone is at home.
"If nobody ever rang your door, that would probably say something about your social life as well."
She added that it remained unclear how much further "anonymised" data was also being collected. cont
https://www.bbc.co.uk/news/technology-51709247