Uses of F4 key

Below are the uses of F4 key.
1) Pressing F4 key will move the keyboard cursor to the address bar(Both in windows explorer and Internet explorer) and also drop down the address combo box.
2) Pressing Alt + F4 will close the application. If no application is opened, the shutdown dialog box will be opened.
3) Pressing Ctrl + F4 will close only the currently opened document in the application. (For example, if you have opened two pdf document in the acrobat reader, only the currently viewing pdf document will be closed and not the acrobat reader application).