Kali has been around for quite some time. Known previously as BackTrack, with releases from versions one to five, Kali Linux was first seen in 2015 and released as Kali 1.0. From 2016 onward, Kali was then named according to the year. For instance, at the time of writing this book, the version used was Kali 2017.2, released in September 2017.
For those running older versions of Kali, or purchasing this book at a later date where new versions of Kali Linux may be available, you can easily update your instance of Kali Linux by using the sudo apt-get update distro command, demonstrated toward the end of this chapter.