Which version of Windows do I have? [duplicate]

I do not know which Windows version I have running on my laptop. How do I find this out? I need to know before telephoning my service provider.

Press Win + R, type winver and press Enter. You will see a dialog with your version of Windows that looks something like this:

Another way is to press Win + Pause/Break which will open System window that also has info on the version of your OS. It might look something like this:

If, for some reason, you wanted to do this from a command line:

systeminfo | findstr /b /c:"OS Name"

(Reference: Find Windows Version from CMD.) It has the added bonus of showing the OS edition. For me, it produces the following:

OS Name:                   Microsoft Windows 8.1 Pro

This works on all versions since XP. You can produce the command prompt with Win+R followed by cmd in the resulting dialog, as mentioned a couple times by other answers.

All versions before XP, if I remember correctly, clearly show the OS version and edition when booting up.

If you will check your edition op your Windows pc, you can right click on start button and select system.

This opens a window where you can find your spec's (specifications) of your computer. You can also use this shortcut Win icon + X.

Comment by @BenN, works this for Windows 8 and newer (this are: Windows 8, 8.1 and 10). For older OS, please check other answers.

Using a Run command Windows Key+R opens the run box, then enter:

control /name Microsoft.System

Hit the OK button.

This will show you the installed Windows version. This Run command works in Vista, W7, W8, W8.1, w10

wmic os get Caption,CSDVersion

Along with the other answers you can run this in the commandline and get an output like:

c:\>wmic os get Caption,CSDVersion /value
Caption=Microsoft Windows 7 Enterprise
CSDVersion=Service Pack 1

CSDVersion may not return anything and isn't strictly needed but it can be useful if you want SP.

More detail here.