Mice, windows and pull-down menus have certainly made computers easier to use. By looking around the screen, it is usually possible to discover what you need to do, without having to learn obscure commands and key combinations. However, this is a very slow and inefficient way of doing things that you need to do often, and over-use of computer mice can also lead to physical pains in the forearm. It can help to learn the keystroke commands for these regular actions. This is easy to do, and soon you won't even have to think about them.

For example, I regularly grab texts from news wires, copy them into Microsoft Word, and save them. The sequence is: Ctrl-A (selects everything), Ctrl-C (copies what has been selected), Alt-Tab (switches to Word), Ctrl-N (creates a new blank document), Ctrl-V (inserts copy) and Ctrl-S (for save). Once you've done it a few times, it takes only a few seconds.

I'm not starting a war against mice. One really useful thing about this string of key combinations is it can be performed with the left hand, so I can keep my right hand on the mouse.

All these keystrokes are worth learning, whichever applications you use. If you are browsing the web, for example, there is no quicker or easier way to open a new browser window than Ctrl-N. The mousy alternative is to move the cursor to the File menu, select New, then move across to Window. Even doing it with keystrokes is fussy (Alt-F, right arrow, Enter). However, if you do that, you will notice that Microsoft has included the Ctrl-N tip on the pull-down menu.

There are four key combinations you should master first, and fortunately they are easy to remember. Use Ctrl-C to copy things (C stands for copy) and Ctrl-X to cut them (the X is like a pair of scissors). Use Ctrl-V to insert what you've copied (the V is an insert sign, upside down), and Ctrl-S to save it (S stands for save).

The same keystrokes may work on other systems, too, though on the Apple Macintosh, you have to press the Command key instead of the Control key. Other useful keyboard shortcuts are provided on the Mac's drop-down menus. The Mac does not have as many shortcuts as Windows, but they are much more consistent across applications: this means they are easier to learn and even more useful.

Another interface convention is to underline a letter to indicate a keyboard shortcut. For example, in Windows, the File menu always has the F underlined. This means that pressing Alt-F will select the file menu, then pressing O on its own will select Open (the O is underlined). A few of these shortcuts are worth knowing, especially if you use Notepad a lot: Alt-F S Alt-F X saves a file and exits, for example. The drawback is that Format has the o underlined because the F has already been used for the File command. It is probably not worth trying to learn that, unless you use it several times a day.

Learning underlines can also be dangerous, because the same keystroke shortcut may do different things in different applications.

Some of the PCs dozen function keys, labelled F1 to F12, are also useful. In Windows Explorer, for example, highlighting a filename and pressing F2 lets you rename it, while pressing F3 brings up a search box. If you high light a folder in the left-hand pane, pressing F5 makes Windows re-read the directory and update the list of files.

Files can also be copied using Ctrl-C and Ctrl-V, just like bits of text.

And on both the PC and the Mac, pressing the first letter of the file you want will take you to the first file that begins with that letter. If there are a lot of files in a directory, this is usually quicker than scrolling to it.

People who suffer from disabilities or strain injuries may want to use keystrokes even for things that most people are happy to do with a mouse. And, indeed, a surprising amount can be done. In Windows, for example, the Alt-spacebar combination provides access to control menus, so you can minimise a program (make it disappear from the desktop) by pressing Alt-spacebar then N. Not many people know that.

Pressing Alt-spacebar then M (for Move) lets you move a window to a new position on the screen. Move the window using the cursor keys and press Enter to accept the new position. Pressing Alt-spacebar then S lets you use the cursor keys to make a window bigger or smaller. Microsoft's aim for certified Windows 2000 programs is that users should be able to perform "every" action from the keyboard, without using a mouse at all.