The unofficial tools are tools that were made by third parties which are not officially supported by Slackware.¬† These tools can be broken into two groups package retrieval and package building.
The main three methods of installation are listed below: To install Slackware from a pre-built package you can use installpkg, upgradepkg, swaret or slapt get.
Other distributions such as debian and redhat choose to modify the original source code with their own revisions prior to distributions, this can add additional functionality but in some cases such as the debian Open SSL packages ( it can result exploits that only effect your distribution which can remain unseen for some time because the original authors (those who know the apps best) were not responsible for the changes or aware of the changes.
This additional liability is something that doen't want hanging over your head when running a production system which requires heightened security and uptime, with Slackware these issues cannot happen all code that is used has been developed by those who know the functionality of the applications best, namely the original authors.
When maintaining a server or even a personal system a certain amount of control must be given to the administrator, the control and simplicity of Slackware package management is what may in fact make you want to try Slackware.
In terms of security and accountability Slackware is excellent because it beings you software in the condition that the authors intended.