What does ~/Library/Application\ Support/Knowledge/ folder do? After upgrading to MacOS Sierra, a new folder ~/Library/Application\ Support/Knowledge/ emerged, I'm not sure what it stores

I already tried to google for it, but only got results for Application Support folder.

Any ideas?
knowledge-agent

/usr/libexec/knowledge-agent writes its databases to
~/Library/Application Support/Knowledge and /var/db/CoreDuet/Knowledge.

This is Siri's proactive knowledge functionality. Siri will read data from the services you enable in System Preferences → Siri → Siri Suggestions &amp; Privacy, writing data it finds useful into the database.