I am using Unity on Windows 7, when in Visual Studio I try to select a keyword (like “Mathf”) and press "Ctrl + ’ " as instructed in the tuorials to open the documentation.
This does not work, not a big isssue since i can search in the documentation manually, but why it does not work? Has this changed in Unity 5 may be (since tutorials haev been recorded on 4.6)
That’s a monodev key command not a vs one
you can get to the docs in visual studio, but it’s quite a few more menu/shortcut transitions and I can never remember the sequence. Far easier to google 
If you have VS tools for Unity (which I believe is included in the latest installations), you want the Help->Unity API Reference menu. It’s got the rather awkward default shortcut of Ctrl+Alt+M, Ctrl+H.
You can change that in the keybind menu - Tools->Options->Environment->Keyboard, and search for commands containing “Unity”.
You can see all of the default Unity-related keybinds here. Quick MonoBehaviour is really convenient.
Thanks to all. In fact all tutorials uso Monodev, while the windows installation installs vs.