Safari 12 is now available for macOS Sierra and High Sierra

INSUBCONTINENT EXCLUSIVE:
Sierra (10.13.6).This new version of the browser, which is the default browser in the upcoming macOS Mojave (10.14) update, comes with a
security updates
password for a service that Safari has saved for another site.This should encourage people to use different passwords for different
websites, rather than using one password for many.Users also have better control over how pop-up windows are handled on websites, and ad
retargeting suppression has been bolstered so that it reduces advertisers' ability to identify unique Mac devices
The web browser also disables any extensions that cause it to perform more slowly by default.So, even if you're planning on upgrading to
features and benefit from the added security.Via OSXDaily