Of the two types of keyboards you are probably interested in, standard and specialized, there are variations in both. With the advent and rise of computer use in homes and by nearly every population of people, there is a computer keyboard to fill virtually every need, preference, and limitation. You first choice is between a standard keyboard and a specialized keyboard.
A standard keyboard refers to keyboards with standard features and key configurations. QWERTY and AZERTY are the standard alphabetical configuration. If you've ever used a computer, you're probably experienced with one of these two setups, QWERTY being the more popular of the two. These two configurations are ideal for simple word processing tasks as well as accessing the Internet, typing emails, or doing basic office work.
Variations in the standard keyboard usually have to do with size and ergonomics. For instance, the Rii Mini Wireless Keyboard is a QWERTY keyboard, but it is the size of your palm and designed for use with wireless devices such as e-tablets or smartphones. On the other side of the spectrum, the Microsoft Natural Ergo Keyboard 4000 is larger than normal but still has the standard setup. The keyboard here is split in the middle and titled to allow the users' wrists to rest in a more natural position.
Specialized keyboards range from those with additional features to those designed for specific languages or populations. For example, the Logitech Gaming Keyboard G110 may appear to be a standard keyboard but, upon closer inspection, you'll notice a number of additional keys called G-keys or gaming keys. These, along with every other key on this keyboard, are programmable to perform a specialized gaming function. There are also keyboards designed for most non-Greek-alphabet-based languages, including Arabic, Chinese, Japanese, and Sanskrit.
The variations often seen in the specialized keyboards are usually population-specific. For example, the EZSee by DC Large Print Computer Keyboard is designed specifically for the sight-impaired. It features large, raised letters and a distinct contrast in color between the keys and the letters. The orbiTouch Keyless Keyboard and Mouse is designed for users with extremely limited mobility in their hands and fingers.