It can sometimes be difficult to know exactly what operating system is installed on the computer. Oftentimes you need to know this information when installing content onto the computer. However, the operating system information is listed in the database of the computer--you just need to know where to look for it.
Power on your computer. More than likely, if you are running a Windows-based computer the operator information is displayed before the system completely boots up.
Click the Apple logo in the upper left corner of the desktop if you are running a Mac. If you are using a Windows computer, skip to the next step. From the pull-down menu, select "About This Mac." In a moment a small window appears in the middle of the screen. Under the Apple logo the operating system version is listed (such as "Version 10.5.8").
Select the "Start" button if you are using a Windows-based computer. Click "Control Panel" and the Control Panel window opens. Double-click the "System" icon. Under the "General" tab the operating system is listed, including the version (such as home or professional), the version and the current service pack.