The Acer Aspire e11 comes pre-installed with either Windows 8.1 or Windows 10 depending on the model, and supports both 32-bit and 64-bit versions of these operating systems. To determine which exact version of the OS is installed on your device, you can open the Start menu and type “winver” into the search bar. This will bring up a window displaying information about your current OS version as well as other useful system details.