Clickstreams and data collection in analytics
Basically clickstreams is a methodology of determining the pathway users are taking through your site.
Whenever a user interacts with your site and its various elements this data is being stored in a log file in Google analytics or whatever analytical platform you are using. In order to achieve this three components are used; page titles, browser cookies, and a web server log file. This log file is processed by Google analytics to create reports in your console.
It’s up to your Google analytics admin to filter and and segment this data to be accurate enough for actionable analysis.