What is WiXWindows Installer XML (WiX) toolset is a bunch of command line tools that allows developers to build Windows Installer packages from XML source code. Due to the special database format of MSI and MSM files, traditionally installation developers needed specialized editors to develop/modify Windows Installer packages directly such as ORCA, Wise, InstallShield. However, by using WiX toolset you only need a simple text editor to start developing Windows Installer packages.
On the other hand, WiX toolset assumes that you already have a good level of Windows Installer knowledge. If you have no experience with the Windows Installer, then the WiX toolset can be a big source of frustration. WiX is a very low-level tool that expects users to have some working knowledge of the Windows Installer.