How to Upgrade Ubuntu 14.04 LTS (Trusty Tahr) to Ubuntu 16.04 LTS (Xenial Xerus)

Starting April 21, 2016, the Ubuntu community will be able to upgrade their existing Ubuntu 14.04 LTS (Trusty Tahr) operating systems to Ubuntu 16.04 LTS (Xenial Xerus), so we’ve decided to give them a head start and learn how to achieve that.