The User-Agent string is sent to each website from your web-browser and contains information about itself. This can be sometimes be used to identify your operating system and the exact version of the web browser that you are running. It is up to the owner of each site to use this information to adjust your browsing experience.
User-Agent CCBot/2.0 (https://commoncrawl.org/faq/) Details Array ( [windows] => 0 [macos] => 0 [android] => 0 [firefox] => 0 [safari] => 0 [webkit] => 0 [x86] => 0 [x64] => 0 [x32] => 0 )
See: session info.