Introduction and OriginKeyboards are essential input devices of a computer that can be both hardware and software based only. These devices help us input data into the computer. The modern day keyboard is based on the old devices such as typewriter, keypunch, and teleprinter. A typewriter as a device where the keyboard was a mechanical device operating using mechanical connections to print on a paper.The keypunch as a device where the user had to manually punch holes in stiff paper cards which would then be read by a scanner and interpreted accordingly.Types of KeyboardStandard Keyboard: It is the standard keyboard attached to PCs.Laptop-sized Keyboard: It is a shorter version of the standard PC keyboard which performs the same functions.Flexible Keyboard: This keyboard is made of materials like silicon which make it flexible. It is so flexible that you can actually fold or roll it. This feature makes these kinds of keyboards portable. Hand-held Keyboard: It is a miniature keyboard which also has a screen for viewing. This is like a mini-computer.Thumb-sized Keyboard: These types of keyboards used to come in old phone models such as blackberry.Multipurpose Keyboard: This is a special keyboard which can perform numerous functions. It is a programmable keyboard which means we can change the key-matrix if we wish. It also has a processor and a screen which makes it a miniature computer.Arrangement of KeyboardAll mass produced keyboards are of QWERTY design. The design of a keyboard is done in such a way that commonly used keys do not overlap or be close to each-other. This is done so that a user can easily type efficiently without worrying about any conflicting keys next to each-other, thus reducing chances of mistyping. However there are also special keyboard designs for professional typer customized to their own needs for increased and efficient typing speed.Working of KeyboardThe keyboard consists a key matrix which recognises which key has been typed. In some keyboards, this key matrix is programmable. When a key is pressed, a switch is triggered which enables the system to recognize which key has been typed and appropriately displays the output. On the basis of these switches, there are two types of keyboards:Mechanical-switch Keyboard: In these types of keyboards, the key is a simple switch mechanism where when the key is pressed, a circuit is completed thus the key is also identified. There are three types of mechanical switch keyboards:Rubber Dome: Here, the keys have a carbon center. The friction is greatly reduced due the rubber used which makes key-pressing comfortable.Membrane: In this type of keyboard, there is a continuous membrane which lies beneath the key matrix. When a key is typed, a pattern is printed on the membrane which completes the circuit and enables the computer to recognize which key has been typed.Metal Contact: Here, there is a metal contact beneath the key which completes the circuit when pressed.Capacitive-switch Keyboard: These types of keyboards measure change in capacitance i.e, stored static electricity. Here the capacitance changes because the distance between key and matrix changes when key is pressed. This enables the system to identify which key has been pressed.Virtual Laser KeyboardA special type of keyboard is a virtual laser keyboard where the keyboard doesn’t really exist. It is a laser projection onto a surface. The IR sensors along with camera track where the user’s hand presses and correspondingly inputs that key. The pressed key is determined by the IR scanner detecting our distance along with the key that the camera cannot see. The key components of this keyboard are:Sensor ModuleIR Light SourcePattern ProjectorThe advantages of this keyboard are:It is portable.It is accurate.It doesn’t need large space.The disadvantages of this keyboard are:It is costly.It cannot be used in bright environments.It cannot be used on uneven surfaces.It is hard to get used to due to the lack of response we feel when we type a key.On-Screen KeyboardThis type of keyboard is pure software-based. These type of computers come in-built in phones and computers these days and are very useful. Here, the user selects keys using touch, mouse, laser pointer, etc.The advantages of this keyboard are:There is no need to fear hardware failure.It provides safety from spyware and keyloggers.It is useful when the hardware keyboard fails due to any reason.Physically-disabled people can use this.The disadvantages of this keyboard are:It is slow: If a user has to type each key with a mouse, typing speed is reduced.Less efficient: There is no proper separation between keys hence typing errors can easily occur.Touch-Screen KeyboardThere are two types of touch-screen keyboards:ResistiveCapacitiveGenerally, the capacitive keyboard is more used because there is clear separation between the keys which reduces typing errors. They function as given in name,when a key is pressed, the change their respective quantities.