Device Manager is a built-in tool in the Windows operating system that allows users to view and manage the hardware devices connected to their computer. It provides a graphical interface where users can see all the devices, such as printers, graphics cards, and network adapters, and check their status. Users can also use Device Manager to update drivers, disable or enable devices, and troubleshoot hardware issues. If a device is not functioning properly, it may be marked with a warning icon, helping users identify and resolve problems quickly.