You may install or run an application directly from an archive. Just enter to an archive and press Enter on setup.exe or install.exe program. When Enter is pressed on an archived file, which has .exe extension WinRAR extracts the entire contents of the archive to a temporary folder and then runs the executable file. When the executable has terminated, WinRAR tests the modification time of the extracted files and if any files were changed or if new files were created, Offers to update the archive and then deletes the temporary folder and its contents.
Some programs may register themselves as the default archive viewer even without asking. If this happens and you want to re-register WinRAR again, select "Settings…" item in Options menu, activate Integration settings dialog, select archive formats to associate with WinRAR and press Enter.
If you need to install WinRAR to a large number of computers, it may be boring to answer to setup questions again and again. In such case you may run WinRAR installation with switch -s to skip all questions and use default settings.