Apple today released Safari 15 for macOS Big Sur and macOS Catalina devices, with Apple introducing support for features that are going to be coming in the macOS Monterey update set to be released laster this year.
Safari 15 introduces a new look for Safari with rounded, more defined tabs and support for transparency, a compact tab bar option that can be toggled on or off, and Tab Groups.
Read more at MacRumors.com