Dvorak is an alternate keyboard layout that strives to increase keyboarding efficiency and reduce physical strain on the hands.
The standard keyboard layout, Qwerty, was created back when typewriters were still in their infancy. It was arranged largely at random, with the main priority being to reduce typewriter jams.
By contrast, Dvorak was designed from the ground up for efficiency. The most commonly used consonants are placed on the home row under the right hand, and all vowels are placed on the home row under the left hand. This reduces finger travel and increases the amount of alternating between hands, resulting in faster typing with less physical stress.
Dvorak was created by August Dvorak and his brother-in-law William Dealey, beginning back in 1914. Nearly twenty years later in 1932, they released their result, the Dvorak Simplified Keyboard.
Actually, yes. According to Wikipedia, August Dvorak is distantly related to Antonín Dvořák, the famous Czech composer.
Very different. Nearly all the letter keys have their position changed, often quite dramatically. Most of the punctuation has been moved around as well.
Instead of listing what has changed, it's easiest to list what hasn't changed:
All other keys have been moved. Some are completely on the opposite side of the keyboard (e.g. "Z"), while others have only moved one space over (e.g. "B").
Direct evidence as to the efficiency of Dvorak is limited. No large scale studies have ever been conducted, and any such study would face numerous difficulties.
The creator of the keyboard, August Dvorak, ran several trials that seemed to prove the keyboard's increased efficency. However, these trials were heavily biased, and not particularly rigorous.
A subsequent independent small-scale study found no improvement for users switching to Dvorak, but this trial too lacked sufficient size and rigorousness to be useful.
Most Dvorak users will attest that they type faster and with less strain than they did with Qwerty. However, since all proficient Dvorak users have invested significant time in learning the new keyboard layout, their views are likely to be biased.
All in all, there's really no hard evidence to say whether Dvorak is more effective. Since a proper test would likely need to find a large group of people who have never touched a keyboard before, the odds are slim that we will ever prove whether Dvorak actually increases efficiency or not.
I can't answer that for everyone. Personally, I switched when I began having hand strain issues with Qwerty. My Qwerty typing style was fast and sightless, but also very ad hoc and self-taught. This unusual "closest finger wins" style of typing likely involved a lot more strain than a "proper", home-row Qwerty style would have.
Since I had been typing for so long by this point, I was unable to learn the correct style of Qwerty keyboard usage — I could not un-learn my style and I kept slipping back into it. Instead, it was easier to just start from scratch and learn Dvorak in the correct home row style of usage.
My finger and hand strain essentially disappeared at that point, and my speed and comfort increased dramatically. However, since my old style of Qwerty typing was grossly incorrect, I cannot really properly compare the two.
This varies from person to person. In my case, it's very confusing and difficult for me to return to Qwerty. If I continue typing for many minutes, I can regain some minor degree of ability.
For the most part, I no longer type Qwerty except in emergencies, such as when fixing others' computers. Even then, I will temporarily switch their computer to Dvorak if my work involves more than a minimum of typing.