As thick-client applications became increasingly complex in the late 1990s, Microsoft realized that its installation technologies had to improve dramatically to reduce installation problems such as component conflicts, and to keep customers from switching to thin-client applications.

The Windows Installer-code-named Darwin-was developed as a better way to install Office applications, but it had broader applicability and was moved into Windows. At the same time, the Windows team was besieged by customer complaints of DLL Hell problems caused by application installation, and began developing a separate technology to solve the problems associated with having multiple versions of the same components running on a single computer.

Windows Installer 1.x

Over the past three years, the Windows Installer has become the standard means by which nearly all Microsoft and third-party client applications are installed on Windows, and it must be used by applications in order to meet Windows logo requirements. However, the Windows Installer is not intended for installation of system-level components, middleware such as Internet Explorer, or server applications, since these usually need to install drivers and other kernel-level components. The Windows Installer was also designed to support installation of client applications on Terminal Server, but this often requires special procedures.