Google Analytics appears to be everywhere, and it was estimated in 2015 that around half of the websites on the Internet use it (see link). Because the European Union requires websites have a cookie notice, you find a lot of cookie notices stating that a website uses Google Analytics.
But, what kinds of information about visitors are being collected by Google Analytics.
1. Demographics - a visitor's age and gender.
2. Interests - affinity categories (identify users in terms of their lifestyles) and in-market categories (identify users searching for certain product categories)
3. Geography - language and location (by country)
4. Behavior - new versus returning, frequency & recency, how long engaged on the website
5. Technology - browser & OS, network
6. Mobile - device types, mobile device type