Computer keyboards have gone through a lot of changes through history. As usual the general public have followed the trend of business which is to provide cheaper products wth greater profits. As such, a hobby group of enthusiasts has been growing ever since the introduction of the membrane keyboard to create a cheap alternative to the mechanical switches that had been in use since creation. The primaary complaints about membrane style keyboards is that they drastically reduced the feedback to the fingers as to whether a key had been actioned or not. The description of a "mushy" texture is often common with membrane keyboards as there is no feedback as to whether a key had actioned even once it had bottomed out. As such, companies started to produce switches that used levers and clips to reproduce the feeling of positive feedback. These gained the name "Mechanical" switches for the mechanical nature that they actioned as apose to the purely electrical stimulation from a membrane. The primary draw back to using mechanical switches is the large cost associated with them, a full set of switches can cost twice as much as a full membrane keyboard. For this reason, in recent years certain companies, such as Logitech, have tried to cross the benefits of a mechanical switch with the cheap production of membrane, adding an artificial mechanical switch to send the message to the membrane that is the actual switch.

Layouts

Due to the costs of building fully custom mechanical keybaords, cut down versions of previously standard 107 key standard keyboard started to become popular. The first thing to be removed was the Function keys but a keyboard with everything but these keys wasn't particularly popular and so the Ten Keyless (TKL) was introduced. This removed the numpad while still keeping the function keys which reduced the footprint of the keyboard by reducing the width. This became very popular especially with gamers as the numpad is very rarely used and makes the overall cost cheaper while still having all the commonly used keys.

Within the community, a goal to try and cut costs and decrease the complexity brought more compact keyboards into mainstream. The 75% removed the numpad the same as TKL but also moved the arrow keys and removed some of the functional keys such as Delete, Home, Page Up, Page Down, Insert and Print Screen. Some of the keys were placed on the side in an extra vertical strip between the arrow keys and rest of the keyboard. This simplififed the PCB greatly as it descreased the gaps between the keys. The 75% became very popular and remains one of the most popular layouts for beginners in the space. 65% was a continuation of the same theory but removes the top Function row of keys and brings the Escape key down to the number row. This layout is the least popular of the common layouts. The final common layout is the 60% and is the most popular in terms of the entusiast space. It removes all the functional keys and the arrow keys, employing the use of of multiple layers. Effectively the same as Control+C to bring back those functions. 

A less popular layout is the 40%, this removes the numbers row, making even heavier use of multiple layers, often having to rotate through 3 layers to get all the functions of a full size keyboard. This will allow a user to have even a numpad.

One of the most bizarre looking keyboard layouts is the ortholinear, this breaks from the standard offset keys to move all the keys into an in line grid. All of the keys are the same shape and height and are often blank. This makes them nearly impossible to use for the average person and so takes a long time to learn.

Split keyboards are also fairly popular, especially for users that desire a more ergonomic design. A wire will connect the two halfs and a lot of the keys that would usually be pressed by the finger will often be used by the thumbs as the design allows for greater use of the thumb. 

The final thing of note is that most keyboards follow the now standard American National Standard Institute (ANSI) while the rest of the world follow variations of the Internal Organisation of Standards (ISO). As most mechanical keyboards are built for the american market and building variations cuts into costs it can often be difficult to get keyboards with the UK ISO layout with the characteristically large Enter, and longer Caps Lock. This issue does not apply to Ortholinear or Split layouts.

Key Caps

The first thing seen by people when they look at the keyboard is the key caps. For this reason the biggest emphasis of asthetics in the keyboard community is aimed at the colour and design of a key cap. While they almost always use the same Latin letters and numbers, the fonts and sizes can change drastically with some even being transparents to allow light to shine through the key cap and illuminate the number or letter. Other keys can use symbols from different languages, Japanese Katakana is quite popular and sometimes replaces the Latin symbols and other times the key has both on. Limited run key caps are built for other communities such as Elvish from Tolkien's universe and Klingon from Star Trek. Other users prefer to use blank key caps either for the aesthetic or because they prefer to use their own layout. Ortholinear, 40% and Split Keyboards often use blanks as they rarely reflect the usual QWERTY layout of a conventional keyboard.

To the average user the shape of key cap doesn't change much and even after taking them off, as long as they are put on in the correct place, other than the obvious keys, the difference in shape is rarely noticed. In reality the shape between the rows can and does vary. Trying to put a row 1 key on the 2nd row will instantly look out of place. This is because the shape of the key is moulded to have the face at a certain angle which is designed for ease of typing. Almost all keys use a very similar shape, meaning that you can take keys from two different sets, mix and match and they will most likely line up. However some sets are designed with much taller or shorter caps. Others are designed to create a different shape to type on. 

Almost all key caps will employ the Cherry MX compatibility design. This is a small cross that slides over the top of the switch with better switches providing a tighter fit therefor creating less wobble in the switches.

The material of key caps is also split into two. PBT is considered the more premium material as it is harder wearing and is more resistance to the natural oils produced by human skin. As it is more resistant it makes the printing of letters and numbers more expensive and can in time be rubbed off. Almost all keycaps on a regular commerical key board will be made from ABS, the plastic is much lighter and and less resistant. If a keyboard has shiny keys from lots of use, this will be because the plastic is ABS, PBT will not become shiny in the same way or at all. The sound of ABS keys is much more subtle as they don't absorb the sound of the switch in the same way so they are far less popular in the keyboard community where the sound is often king. 

Key caps can also be manufactured in two different ways. The cheap and most common way is single injection molded, this means the key is made from one injection of plastic and often made to be quite thin so they solidy quickly. This makes them often quite sloppy and less premium. Double injection molding is the most popular method as it employs a second injection of plastic after the first has set to reinforce the switch and allow for a crisper finish. While almost all key caps are made in a type of plastic, some enthusiasts use keys made of aluminium though these cause problems as the Switch springs are not designed for this kind of weight and can cause early failure. There are also a small group of people who like to use wooden switches, these also come with a more obvious problem in that Wood is far less resistant to oils than plastic or metal. This means that the original aesthetic can be quickly ruined and cleaning the Caps can be far trickier as the oils will seep into the wood grains.

The final thing worth mentioning about Key Caps is that compatability between ISO and ANSI layouts can be difficult. For the most part the alphabetical and number keys can be interchanged shape wise, the function keys can be very different. Some numbers also have the sub symbols in different places such as the # dollar sign being under the 3 on ANSI as appose to under the @ on UK ISO. The variations also change between Apple and Windows, though thankfully the symbol location for Apple does no change between UK ISO and ANSI as the # is under the 3 for both. Some key cap kits are sold specifically for the UK ISO and some will come with conversion kits for ISO in the kep pack and some will be sold seperately. Requiring you to buy the full kit and then a conversion leaving you with spare keys for ANSI that can't be used. The argument as to whether the ANSI or UK ISO is better boils down completely to personal preference. While it takes very little time to adapt to either, my personal opinion is that the ANSI has a better Left Shift key and the UK ISO has a better Enter key. Overall I prefer to use UK ISO as it was I have used the most but I dont let this prevent me from buying new keyboard if I can only buy them in ANSI.

Below is a list of key cap manufacturers:

Tai-Hao
GMK

Switches

The switches are largely considered the most important part of a mechanmcial keyboard, as they are the part that makes them "mechanical". The key caps, board, and everything are all parts that while may make the final product look nice, have far less impact on the typing feel. Switches are broken up into three major catagories: Clicky, Linear and Tactile. There are hundreds of types of different switches ranging from common to ultra enthusiast. For the remainder of this document I will only talk about the more common switch manufacturers. Switches are often described with graphs of their distance on the X and force applied on the Y. The distance is in regard to the toal movement of a switch in its resting position to its fully actuated position. The travel is often split up into pre-travel and total travel. The pre-travel notes the distance required before the switch is actuated, the total is therefor the distance the switch will travel before hitting the bottom. This method of actuating before the switch hits the bottom gives the perceived notion of faster typing as the letter will appear on the screen before the switch has hit the bottom of the board. The force required for a switch to acctuate also varies drastically as some people are heavy typers and require heavy switches while some people find that their fingers get tired if the switches are too heavy. The distance travelled is usually measured in millimeters (mm) and the force required is measured in centinewtons (cN). Another thing to note is that switches often have different responses on the upwards movement than on the down. This is due to the mechanism having a ratcheting style that will acctuate at different points. Switches are made up of the Upper Case, Lower Case, Peg, Clip and Spring. Switches use a naming scheme made up of Brand + Colour. An example of this is Kali Gold where Kali is the brand and Gold is the type. Some brands keep to a specific colour scheme, making the type of switch easy to recognise however a lot of other brands do not keep to this scheme. That being said, the primary 3 of Red, Brown and Blue are rarely changed.

Linear switches are designed to have no tactile bump. Instead of trying to imitate the clicky response of original keyboards these switches seek to improve on a new style that keeps the switch movement as linear as possible. This is not to be confused with membrane. The linear switches do not require any sudden increase on force at any point in the switch which is common in membrane and gives them the characteristic "mushy feeling". These switches are the fastest style as there is no contension with any form of ratchet, allowing them to be pressed and released quickly. This makes them popular with gamers as it is common to require pressing the same key quickly instead of pressing lost of different keys as would be required in typing. The most commonly recognised colour for Linear switches is Red, these switches have a relatively low weight requirement and a characteristically longer pre-travel compared to the total travel. This is to allow the same key to be pressed repeatedly without having to bring the whole key up to reset. As such Red switches are usually marketed at Gamers but the benefit to a gamer is rarely recognised. Linear switches are also by far the most quiet as they do not provide any form of click due to there being no form of ratcheting. All the sound is created by the switch mechanism hitting the bottom.

The most popular switch for people who arn't really enthusiasts but want a better keyboard is the Tactile switch. Physically they are very similar in construction to Linear switches with the only real difference that they have a small bump where the switch acctuates. This can be popular with typists as it gives a physical feedback via the fingers when the switch has actuated and the signal has been sent to the device. This slight bumb causes the force requirement for the switch to differ slightly to a linear switch. After the pre-travel the force required will increase slightly to move the mechanism over the bump. It will continue as the same force as before until the bump has been passed and the final distance will have a short period of less force requirement. The most common colour for tactile is Brown. On paper the Brown is usually very similar to red with similar pre-travel and no audible click. The only variation is that they usually require slightly more force due to the bump. This is not to say that Tactile are Heavier than Linear as either can be built to be far heavier or lighter than the other.

The loudest, most complicated and most notrious switches are the Clicky switches. These are what most people imagine when they thing about mechanical keyboards as they have that loud clicking actuation sound that resembles an IBM Model M, which is often considered the Holy Grail of original mechanical keyboards. While on the outaside, a Clicky switch looks much the same as a Linear or Tactile, the mechanism inside is far more complex. Linear and Tactile are both made up of one molded piece of plastic for the Peg. For a Clicky switch, the Peg is broken into two pieces and therefor requires two springs. This is so that when you are pressing down on the Peg the bottom half of the Peg will slide up until it reaches the top, enough force is applied to overcome the bump and then the bottom half of the Peg will shoot down, stiking the bottom of the switch creating a click noise. This noise can often sound a little disjointed at first as the switch actually actuates just slightly before the click is heard. This sliding click motion gives the key a very odd looking Weight Distance graph at least compared to a Linear or Tactile. A lot of force is required to overcome the two set of springs and then push the bottom half over the tactile bumb. Once the bump has been passed the force required will drop dramatically as there is now only spring but once the bottom half has clicked it will rejoin the top and therefor a slight bit more pressure is required to bring the switch all the way down to the bottom. From purely looking at the graph, the Clicky switches look by far the worse but this is the key reason as to why a document like this cannot fully explain a keyboard. To know a keyboard is to use it as you cannot understand what these words feel like without typing on the switches. The most common Clicky switch is the Blue and is one of the loudest switches even among Clicky. This can often be seen as obnoxious and in a public or shared office setting there is a good chance that both the keyboard and the user will go for flying lessons. Use Blue switches at home.

With the exception of a few highly enthusiast switches, all switches use the Cherry Compatible design. Vertically this looks like a cross which the key cap can slide down onto. Some of the more premium switches go a step futher such as the Kalih Black Box. This adds a square around the cross to give a collar to the key. This adds a lot stability to the Switch + Key mechanism.

The final thing of note about switches is the destinction between Normal and Hot-Swappable. Hot-Swappable are far more expensive and simply mean that they can be pulled from the keyboard unlike the normal switches that are wired and sortered to the board. There will be more detail on this in the PCB & Controller section.

Below is a list of Switch manufacturers:

Cherry
Gateron
Kailh

Case & Backplate

The case is the second most important part of the keyboard in terms of aesthetics after the Keycaps. It is the part that keeps the PCB, Switches and Controller all together. Some Cases will have a connection such as USB-C Femake on the case while cheaper manufactured keyboards will simply have the cable poking out. Other cases will have switches on them, this will often be to switch the keyboard between Windows and Mac mode. This can be highly favourable solution for people who run both Windows and Apple products. If the keyboard can run in a wireless mode it will have a Battery inside, therefor these keyboards will have a switch for the Wired, Bluetooth and Off. Others may include buttons to change the LEDs. The Case also includes the standoffs that allow a user to raise or lower the angle of the keyboard, these are usually made of plastic and the more premium solutions will have 3 heights. If the hinges or the plastic is thin then this can introduce flex and bounce into the keyboard which is a problem 

Most cases used by manufacturers are made out of a plastic which can vary the quality of the build but is almost always considered the least premium option. It is the lightest option but also the most flexible. When typing on a keyboard the goal is to a solid feedback through the fingers and so the aim is to make the keyboard as rigid as possible. Therefor the less the flexible the better the typing experience in general. Aluminium is the next most common material as it is relatively cheap. It still has a little flexibility but is far more rigid compared to plastic and this becomes completely disregarded beyond a certain thickness. The trade off is that aluminium is also far heavier, though as keyboards are rarely moved around much this isn't often condiered a big problem. Infact, a lot of people actually prefer a heavy keyboard, especially heavy typers as it means that the keyboard will move around less over long periods of time. Aluminium also gives the keyboard a far more premium feeling in terms of weight and touch when compared to plastic. Wood is used by enthusiasts who have a desire for a certain aesthic, while there is no reason to choose wood for its physical properties over aluminium, the physical appearance granted by wood to a keyboard is undeniably beautiful. Because of this, a lot of aluminium cases will have a wood veneer to give it the same physical appearance but upon picking it up the weight differnce is apparent immediately. People that use wooden cases will often have to build the case themselves, therefor they will be aware that proper maintenance of a wooden case can be difficult and will be more heavily effected by sunbleaching over time then plastic. Among some enthusiasts, the blank bottom of the case is used to put intricate designs and pictures on the bottom. Though they will never be seen during use, they are popular as almost secrets that only other enthusiasts would know to look for.

All keyboards require a case but not a Back Plate. The Back Plate is used to add aditional support and rigidity to a keyboard, often used with plastic cases. Back plates are also common with people who have either designed their own PCB or wired their own as it will hide the ugly circuitry. 

Stabalisers & Lube

Within the enthusiast community their is a subset of users that take the hobby further. These are the people that will design their own PCB or wire their own keyboard. It is common therefor to add aditional parts to the keyboard that increases the experience but also increases the complexity. One of these additions is adding stablisers, these are metal bars that are added to the switch for long keys. The most common key is the Space Bar but other keys include the ANSI Enter. 

Another addition is to add a Lube to the switches. This is almost exclusively done for Clicky style switches as the Peg is split up into two parts and lube is applied between to allow the collar to slide easier and create a smoother action. The lubing of switches is considered the rabbit hole of keybaords as at this point the information and difference between lubes is so minor that it all becomes personal preference.

Cables, Connectors & Wrist Rests

Standard manufacturers don't usually provide a keyboard with a cable that can be detatched, this is to lower manufacturing costs. The keyboard community likes the customisability and so have a small USB port on the Case. The most common now is USB-C but previously USB-B Mini was used. This allowed the choice of different coloured cables. The cheapest solution is just a plain rubber shroud but the standard within the community is to have braided cables with multiple colours woven in to match the colour scheme of the keyboard or the whole desk. The cheapest solution is to just have a strait cable but as this can often create cable mess, a coiled cable has become popular in recent years. This allows the cable to stretch to be as long or as short as needed without creating pools of loose wire.

For almost everybody, including enthusiasts the USB-A connector on the other end of the cable is by far the most popular. However a few people still prefer the old original PS/2 connection. There is no real good reason to use the PS/2 as if you pull this connection out while the Computer is powered on it can cause a crash. Support for PS/2 is also dwindling. Keyboards do not need any more the USB-A 2.0 however a lot of manufacturers provide USB-A 3.0. 3.0 is only required if the keyboard includes some sort of USB Hub.

The final part of a keyboard isn't strictly part of the keyboard but is often used with one. The wrist rest has become a staple for keyboard users over the years, especially people who type for a long time. Wrist rests can help prevent things like RSI but mostly they are just for comfort and for some people aesthetics. The true wrist rests to prevent RSI are made of a soft memory gel but some are made from foam. The more popular materials with enthusasts is Wood and even sometimes marble or glass.