IF YOU LIVE and work online, you're creating electronic selfies all the time. If you want to see what those selfies show about you, click into several profiling services.
Google forms a profile about you in order to show you relevant advertising. I look at what Google thinks I like by viewing https://www.google.com/ads/preferences/
For the record, Google thinks I'm interested in bicycles books, Entertainment News (one of my default pages is Yahoo! News), dance & electronic music (because I bought those kinds of tracks from Google), finance (technology stories are often carried under "finance" headings), fitness (I teach fitness students), food & drink, hair care, hygiene & toiletries, make-Up & cosmetics, mobile phones online video pop music, rap & hip-hop and shooter games.
I stopped carrying my Android phone three months ago, so Google's location history function depends upon my Chrome browser settings. Google has constructed a rather accurate map of my actual location based on what I see at https://maps.google.com/locationhistory
Google has saved 21,750 search queries I have made. I use the tracking at https://history.google.com as part of the fact-checking process needed to keep academic content fresh and relevant. I check text queries and YouTube queries. https://www.youtube.com/feed/history/search_history
Whenever I travel, I check Google to see if anyone might have accessed my Google account. I've seen IP addresses and city locations appear in Google Security settings that have caused me to change account passwords. You can see more here:
When you burrow into the security activity, you can also see the exact type of permissions granted to various apps. I routinely revoke access to apps that I no longer use.
Gina Trapani talks a lot about how Google lets you export all your data (i.e., bookmarks, emails, contacts, drive files, profile info, your youtube videos, photos) and if you want to do that, start here: