The code necessary to run publications was put in a single DLL file called the runtime module. This module is a dynamic-link library that allows publications to be run: it works like the Visual Basic DLL runtimes, Adobe Flash player, Microsoft SilverLight, Java Runtime Environment, Windows Installer runtime, etc...
When you start a publication EXE file, the latter will look for the runtime module and call it in order to run the publication.
Since this runtime module is not available on all user computers, it should normally be merged within the publication .exe file, so you get a single stand-alone .exe file to distribute to your end users (without the need to give them any additional file). However, this runtime takes about 1 Mb so HTML Executable gives you the choice not to merge it. To save a lot of bytes, especially if you create and distribute multiple publications, the runtime module may not be merged into the publication .exe file. In this case, you will get "light" .exe files. In return, you have to distribute and install the shared runtime module only once.
If the runtime module is NOT merged:
If you decide not to merge the runtime module, you must provide your end users with it. But do not worry, there are a lot of solutions. The runtime modules are available in small Setup distribution files, ready to be distributed along with your publication files; or they can be downloaded for free from the HTML Executable website (see below for URLs). You can even upload them to your websites if you wish.
The runtime module needs to be installed on the user computer like any program (it also comes with a uninstall program so end users can remove it if they do not need it anymore). Note that it does not contain any spyware, system and shell add-ons; it won't hurt or cause damage to the user system. This is just a regular single DLL companion file called by publications.
If the runtime module is not found on the user computer when a publication is run, then the publication will display a warning message along with instructions about how to obtain the runtime module for free. You can of course edit these instructions by clicking "Edit Instructions Text" in HTML Executable.
If the runtime module is merged:
When it is run, the publication EXE file tries to locate its runtime module on the user system. If it is not found, the publication will first unpack the runtime module from its data to a temporary location and call it. The runtime module is automatically removed when the publication closes, so no trace is left on the user computer.
More information about the HTML Viewer Runtime module
More information about the IE Runtime module
Merge modules for Windows Installer
Merge modules (MSM) are a feature of Windows Installer that provides a standard method for delivering components, insuring that the correct version of a component is installed. A merge module contains a component, such as a .dll, along with any related files, resources, registry entries, and setup logic. To install the information delivered by a merge module with an application, the module must first be merged into the application's .msi file.
All runtime modules of HTML Executable are also available as merge modules if you wish to author a Windows Installer package for your application/publication.