What is F1 to F12 Function Keys in Keyboard And Their Usage

A function key is a key on a computer or terminal keyboard which can be programmed so as to cause an operating system command interpreter or application program to perform certain actions, a form of soft key. On some keyboards/computers, function keys may have default actions, accessible on power-on.

F1
Almost always used as the help key, almost every program will open the help screen when this key is pressed.
Enter CMOS SETUP
WINDOW KEY + F1 would open the Microsoft Windows help and support center.
Open the TASK PANE
F2
In Windows commonly used to rename a highlighted icon or file.
Alt + Ctrl + F2 opens document window in MICROSOFT WORD.
Ctrl + F2 displays the print preview window in Microsoft Word.
Enter CMOS SETUP.
F3
Often opens a search feature for many programs including Microsoft Windows.
In MS-DOS or Windows command line F3 will repeat the last command.
Shift + F3 will change the text in Microsoft Word from upper to lower case or a capital letter at the beginning of every word.
F4
Open find window.
Repeat the last action performed (Word 2000+)
Alt + F4 will close the program currently active in Microsoft Windows.
Ctrl + F4 will close the open window within the currently active window in Microsoft Windows.
F5
In all modern INTERNET BROWSERS pressing F5 will REFRESH or reload the page or document window.
Open the find, replace, and go to the window in Microsoft Word.
Starts a slideshow in PowerPoint.
F6
Move the cursor to the ADDRESS BAR in INTERNET EXPLORER and MOZILLA FIREFOX
Ctrl + Shift + F6 opens to another open Microsoft Word document.
F7
Commonly used to spell check and grammar check a document in Microsoft programs such as Microsoft Word, Outlook, etc.
Shift + F7 runs a Thesaurus check on the word highlighted.
Turns on Caret browsing in Mozilla Firefox.
F8
Function key used to enter the Windows startup menu, commonly used to access Windows SAFE MODE.
F9
Opens the Measurements toolbar in Quark 5.0.
F10
In Microsoft Windows activates the MENU BAR of an open application.
Shift + F10 is the same as RIGHT CLICKING on a highlighted icon, file, or Internet link.
Access the HIDDEN RECOVERY PARTITION on HP and Sony computers.
Enter CMOS SETUP
F11
Full-screen mode in all modern Internet browsers.
Ctrl + F11 as a computer is starting to access the HIDDEN RECOVERY PARTITION on many Dell computers.
Access the HIDDEN RECOVERY PARTITION on eMachines, Gateway, and Lenovo computers.
F12
Open the Save as the window in Microsoft Word.
Shift + F12 save the Microsoft Word document.
Ctrl + Shift + F12 prints a document in Microsoft Word.
Preview a page in Microsoft Expression Web
Open FIREBUG