Alternatively known as Control 4 and C-4, Ctrl+4 is a shortcut key most often used to switch to the fourth tab in a browser or another program with tab support.
How to use the Ctrl+4 shortcut key
The "1" used with this shortcut is the "4" at the top of the keyboard and not on the numeric keypad.
Ctrl+4 in Microsoft Excel
You can also use the Ctrl+U shortcut to italicize text in Excel.
Using Ctrl+4 in an Internet browser
If you only have three tabs open, pressing Ctrl+4 does nothing.
Related keyboard shortcuts
Below are links to related keyboard key and keyboard shortcut pages.