Mobile device data and HTML5, what and where to use?

Question

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Relatively recently, I saw a handy tutorial about new (conditionally) possibilities in web development, where all types of user data collection are conveniently collected, for example, from a mobile device, from network and battery status to access to vibration, or cameras.
Are such features often implemented, for example, to reduce the load on the system? If necessary? Recommend articles or something similar,
PS saw the application where everything was collected, I didn’t remember the name, I would like to find it)