Since long before computers existed, keyboards have been one of the most common methods of writing. First used on typewriters in the 1850s, keyboards have gone through several internal design changes: Early computer keyboards used fragile metal filaments under each key. Later designs used springs or mechanical switches, while most modern devices use squishy rubber domes atop a circuit board. Throughout all their iterations, and despite the growth of technologies including touch screens and voice recognition, keyboards remain a standard input device due to their speed and accuracy.
Advantages Over Touch Screens
Between smartphones, tablets and the touch-friendly interface added in Windows 8, touch screens have become a common input method. In most respects, however, touch serves more as a replacement for a mouse than a keyboard. Typing on a touch screen requires an on-screen keyboard, which lacks the tactile response of a real keyboard and places your hands at an awkward position. On-screen keyboards also make it hard to type quickly, as closely timed taps are often misinterpreted as swipes. Rather than rely entirely on touch, touch-screen PCs still support real keyboards, and even many mobile devices work with detachable keyboards.
Advantages Over Voice Recognition
In the early 1990s, at the dawn of voice recognition, setting up a voice system often required extensive training and the use of an unnaturally flat voice -- not to mention hundreds or thousands of dollars for hardware and software. Today, speech recognition comes built into Windows 7 and 8, and only requires a few minutes to set up. Voice offers a raw speed competitive with typing, but at a cost of accuracy: The potential for misheard words forces you to carefully check over each document you narrate. Some speech recognition systems, such as the one included with Windows, don't automatically add punctuation, further reducing efficiency compared to a keyboard.
Advantages Over Pen Input
Drawing tablets and some touch-capable computers support writing with a stylus. Though primarily used for art and design work, this technology doubles as a text input method with few major drawbacks. With programs such as Microsoft OneNote, you can write freehand on your computer, just like writing in a notebook. OneNote can convert writing into text usable in other programs, but with less than perfect accuracy -- if you have messy handwriting, the computer can't read what you write. Writing by hand also takes longer than typing on a keyboard, once you learn how to type correctly.
Typing on a keyboard is a fast and accurate way to use a computer, but typing efficiently requires memorization of key positions and practice with using all your fingers. For someone who has little experience with a computer, such as a young child, a touch interface can be more intuitive. On the other end of the spectrum, people who spend hours a day on the keyboard can suffer from repetitive strain injuries, and might benefit from voice recognition. Some manufacturers sell ergonomic keyboards, designed to alter the posture of a typist's hands, but a study at the University of Pittsburgh found that these keyboards were no more helpful in treating existing injuries compared to normal keyboards.