The Ctrl (Control) and Alt keys on the bottom row of a keyboard, for instance, are used in conjunction with the mouse to provide a larger number of menu functions, options and keyboard shortcuts.
The keys on the top row also have particular functions ~ the F1 key, for example, brings up Help files if the user needs assistance from the built-in manual. The other F-keys have particular functions assigned to them by software applications in order to extend the functionality and give users more options and control over what they do.
Some applications, such as Microsoft Word, lets the users assign tasks to F-keys to save time and improve productivity. These are called Macros. Essentially, the user shows the computer once what they want the F-key to do by recording a macro. Next time, the user can save lots of clicks and mouse-work simply by hitting the appropriate F-key and having the task done for them automatically.