Based on the Debian GNU/Linux 10 “Buster” operating system series, Tails 4.18 contains updated Intel (intel-microcode 3.20210216.1~deb10u1) and Linux firmware (firmware-linux-nonfree 20210315-2) packages to ensure support for the newest hardware (e.g. Wi-Fi, graphics, networking, etc.).
It also ships with the latest Tor Browser 10.0.16 web browser to facilitate anonymous surfing of the World Wide Web, as well as the Mozilla Thunderbird 78.9.0 open-source email client, which is a bugfix release that introduces various improvements around the Address Book, Calendar, Add-ons Manager, and email notifications.