A hardware interface to insert text into various digital fields. The keyboard is a necessity to getting work done on the computer. Even in a world full of tablets, the feel of a hardware keyboard is much appreciated. Used for shortcuts to pace up work or for movement in games, there is no dirth of the applications of a keyboard in the digital arena.
An essential tool
It would probably be difficult to find a computer in any size that doesn't need a keyboard even tablets that have touch screen keyboards have external keyboards that are attachable through a wire, at times wireless or with a specific port for said tablet. There are models which also have a mouse trackpad built into them to make the user's workflow more efficient, though an external mouse generally works better for heavy tasks.
Sizes, kinds and builds
Available in various sizes depending on what your need is whether you want one that is generally used in one place or something you tend to carry with you. For portability's sake there are keyboards made out of rubber that roll up nicely or foldable ones that are in 3 sections and become a small pad shaped thing you can easily slide into a laptop case. Membrane keyboards are not as snappy as the mechanical ones which is why gamers tend to prefer the mechanical keyboards as they are more exacting with the technical performance of the keys, due to the build these also tend to be a bit more costly. Mechanical keyboards are also more durable and are considered good high-end keyboards.
More rare keyboards
Projection keyboards are an innovation that displays a virtual keyboard on any surface and when a user taps a key the optical sensor camera picks up the finger movement which is then translated into action by a computer software, this was invented by engineers at IBM. Other interesting ones are the ergonomic keyboards which are a more a hardware design variation, one is the raised 'contour' kind which allows for the hand to be at a more comfortable angle while you type. The other is the split keyboard which has the keys separated into two or three groups in a 'V' shape letting the user type in a more natural open shoulder posture.
Which keyboard works for who
The keys really define how you type from the older larger keys to the more flat ones we are used to today, having the one that works better for you is important so you can work at a higher speed and more efficiently. It is essentially a tool which means having the one that fits your need and feel is crucial. The slightly more fancy ones also have keys that light up so if you are working in a low light environment you can see the keys a lot easier and not need to find where your fingers are tapping at in the dark.
These days it is more common to find keyboards that connect through a USB cable making the universal applicability easy unlike before when there was a PS/2 connection. A4 Tech, Logitec, Redragon and Rapoo are a few of the brands that are available to users.