Ubuntu 16.04 Extended Security Maintenance
Canonical provides Extended Security Maintenance (ESM) for Ubuntu 16.04 LTS. The support lifecycle of ESM is tracked on the Releases page.
What's covered with ESM?
During the lifetime of an Ubuntu release, Canonical provides security maintenance. Basic Security Maintenance covers binary packages that reside in the 'main' and 'restricted' components of the Ubuntu archive, typically for a period of 5 years from LTS release. This FAQ entry contains more information.
For Ubuntu 16.04 LTS, where technically feasible, Canonical will provide extended security maintenance to all binary packages that reside in the Ubuntu Main Repository for 64-bit x86 AMD/Intel architectures. See the service description for additional details.