Adam Conrad say in mail of ubuntu release announce :

The Ubuntu team is very pleased to announce our sixth long-term support release, Ubuntu 16.04 LTS for Desktop, Server, Cloud, and Core.

Codenamed "Xenial Xerus", 16.04 LTS continues Ubuntu's proud tradition
of integrating the latest and greatest open source technologies into a
high-quality, easy-to-use Linux distribution. The team has been hard at
work through this cycle, introducing new features and fixing bugs.

Ubuntu 16.04 LTS is the first long-term support release available for
the new "s390x" architecture for IBM LinuxONE and z Systems, as well
as introducing the new Ubuntu MATE community flavour.

The Linux kernel has been updated to the 4.4.6 longterm maintenance
release, with the addition of ZFS-on-Linux, a combination of a volume
manager and filesystem which enables efficient snapshots, copy-on-write
cloning, continuous integrity checking against data corruption, automatic
filesystem repair, and data compression.

Ubuntu Desktop has seen incremental improvements, with newer versions of
GTK and Qt, updates to major packages like Firefox and LibreOffice, and
stability improvements to Unity.

Ubuntu Server 16.04 LTS includes the Mitaka release of OpenStack, along
with the new 2.0 versions of Juju, LXD, and MAAS to save devops teams
time and headache when deploying distributed applications - whether on
private clouds, public clouds, or on developer laptops.

Ubuntu 16.04 LTS introduces a new application format, the 'snap', which
can be installed alongside traditional deb packages. These two packaging
formats live quite comfortably next to one another and enable Ubuntu to
maintain its existing processes for development and updates.

The newest Kubuntu, Lubuntu, Mythbuntu, Ubuntu GNOME, Ubuntu Kylin,
Ubuntu MATE, Ubuntu Studio, and Xubuntu are also being released today.
More details can be found for these at their individual release notes:

https://wiki.ubuntu.com/XenialXerus/ReleaseNotes#Official_flavours

Maintenance updates will be provided for 5 years for Ubuntu Desktop,
Ubuntu Server, Ubuntu Cloud, Ubuntu Core, and Ubuntu Kylin. All the
remaining flavours will be supported for 3 years.