Kali Linux (Kali) is the successor to the BackTrack penetration testing platform that is generally regarded as the de facto standard package of tools used to facilitate penetration testing to secure data and voice networks. It was developed by Mati Aharoni and Devon Kearns of Offensive Security. 

In 2018, Kali had four major releases—as of December 2018. The Kali 2018.1 release was on Feb 6 2018 with kernel 4.14.13 and Gnome 3.26.2. The Kali 2018.2 rolling release was on April 30 2018 with Kernel 4.15 that beats the Spectre and meltdown vulnerabilities on x64 and x86 machines, and Kali 2018.3 on August 21 2018 just after the Hacker summer camp. This brings the kernel version to 4.17.0 with minimal addition to the kernel and the final release Kali 2018.4 for the year was on Oct 29 2018 with an experimental Raspberry Pi 3 image that supports 64 bit mode and updated packages of other tools.

Some features of the latest Kali include the following:

• Over 500 advanced penetration testing, data forensics, and defensive tools are included. The majority of the tools are eliminated and replaced by similar tools. They provide extensive wireless support with multiple hardware and kernel patches to permit the packet injection required by some wireless attacks.
• Support for multiple desktop environments such as KDE, GNOME3, Xfce, MATE, e17, lxde, and i3wm.
• By default, Kali Linux has Debian-compliant tools that are synchronized with the Debian repositories at least four times daily, making it easier to update packages and apply security fixes.
• There are secure Development Environment and GPG signed packages and repositories.
• There's support for ISO customization, allowing users to build their own versions of customized Kali with a limited set of tools, to make it lightweight. The bootstrap function also performs enterprise-wide network installs that can be automated using pre-seed files.
• Since ARM-based systems have become more prevalent and less expensive, the support for ARMEL and ARMHF in Kali to be installed on devices such as rk3306 mk/ss808, Raspberry Pi, ODROID U2/X2, Samsung Chromebook, EfikaMX, Beaglebone Black, CuBox, and Galaxy Note 10.1 was introduced.
• Kali always remains an open source project that is free. Most importantly, it is well supported by an active online community.

While pentesters can prefer any type of operating system to perform their desired activity, usage of Kali Linux saves significant time and prevents the need to search for packages that aren't typically available for other operating systems. Some of the advantages that are not noticed with Kali during a red team are the following:

• One single source to attack various platforms
• Quick to add sources and install packages and supporting libraries (especially those that are not available for Windows)
• Possible to install even the RPM packages with the usage of alien

The purpose of Kali Linux is to secure things and bundle all of the tools to provide a single platform for penetration testers.