Windows Installer is a software component used for the installation, maintenance, and removal of software applications on Microsoft Windows operating systems. It provides a standardized method for managing the installation process, ensuring that applications are installed correctly and can be easily updated or uninstalled. The Windows Installer uses a package format called MSI (Microsoft Installer) to define how software should be installed. This includes information about files, registry settings, and other resources needed for the application. By using Windows Installer, developers can create reliable installation packages that simplify the user experience.