Google Analytics is Google's web analytics service, part of the Google Marketing Platform. Organisations use it to measure how visitors and customers interact with websites and apps across devices and platforms. According to Google, it offers measurement of the customer journey, machine-learning insights, flexible reporting, cross-platform attribution and integrations with Google Ads, Search Ads 360, Display & Video 360, Google Cloud and Search Console. Analytics 360 is a higher tier for larger enterprises. The service is delivered as a web application; there is no self-hosted edition.
Google is a US company, so the data falls under US jurisdiction, including the CLOUD Act. Google states that Analytics does not store individual IP addresses from users in the EU, Switzerland or the UK; IP lookups for these regions are performed on servers there before traffic goes to Analytics servers for processing. The documentation does not say where that processing takes place. The service is not open source.