Windows 9x refers to a series of operating systems developed by Microsoft during the 1990s, including Windows 95, Windows 98, and Windows Me. These systems were designed for personal computers and were known for their user-friendly graphical interface, which made it easier for users to navigate and manage files compared to earlier text-based systems. The Windows 9x series introduced features like the Start menu, taskbar, and plug-and-play hardware support, which simplified the installation of new devices. Although they were popular for their ease of use, these operating systems had limitations in terms of stability and security, leading to the eventual transition to the more robust Windows NT architecture.