To understand today's world of mechanical keyboards, we'll have to go back to the beginning — back to when typewriters and typesetting were viewed as radically new concepts.
In the world of typesetting, the only real requirement for where keys should be placed was that you could spell the word "typewriter" with the top row. The reason for this was so that Remington salespeople could impress their customers with how well their new contraption worked.
The mechanical keyboard of today is essentially the logical progression of the typewriter - optimizing all of the minutiae associated with allowing words and characters to flow from your brain onto a physical (or now virtual) medium.
By the 1960's, the typewriter slowly evolved into the early makings of the first computer. Early computers were a costly endeavor, requiring a full team of engineers to build just one. Lacking in popularity, the few companies who took the time to build computers, also took great pride in their craft. With a focus on quality and craftsmanship, the effort put into building a computer was mirrored in the construction of the keyboard that controlled it. Keyboards were the only link that any end user had to their computer, and it was incredibly important that the tool they used on a daily basis was of superb quality and design.
The Great Keyboard Schism
Somewhere in the 1980's, there was a dramatic split in the world of keyboards, when manufacturers began optimizing for cost at the expense of quality. The result was a new wave of inexpensive keyboards made with cheap printed rubber-domes, letters or legends that rubbed off and plastic that absorbed the oil from your skin.
Fortunately, there were still enough people who cared about their primary computer interface tool to keep the movement for high-end keyboards alive. Today, many professionals, programmers, gamers, and a growing segment of the everyday population are opting for keyboards with a higher build quality over the myriad of cheaper alternatives.
Mechanical Keyboard Switches
So what makes a mechanical keyboard different? The secret lies in the switch beneath the key. Most of the keyboards you'll find at your local electronics store will be layered with a rubber membrane underneath the key. The membrane is made up of collapsible rubber domes that act as "switches" to connect circuit traces. This dome mechanism requires users to push the membrane down completely to activate the circuit, which means more strain on the fingers and slower typing speeds. Rubber membranes are quick to wear out and result in a relatively short lifespan for your keyboard.
Mechanical keyboards, on the other hand utilize physical switch mechanisms, which are made up of a plastic stem, two metal contacts and a spring. Once a key is pressed, the stem pushes down on the spring allowing the metal contacts to touch and register an "actuation".
Unlike rubber dome keyboards, which require you to "bottom out", or effectively hit the table, mechanical switches allow you to press the key only slightly, resulting in less fatigue and faster typing speeds. Also, due to Cherry's accurate manufacturing tolerances, each switch has a lifespan of 50 million actuations, which means that mechanical keyboards can last for decades with normal use.
When it comes to switches, there are three main criteria that matter when deciding which switch is right for you: Linear, Tactile Clicky, and Tactile Non-Clicky.
Linear: Linear means that there is an even amount of force required to press down a key switch. There is no feedback to your fingers when you hit the "actuation point" and therefore, the only way you know a keystroke has gone through is when you see the effects on your screen. The most common linear switches are Red and Black switch types, both of which are considered highly desirable for gaming as they allow for rapid key presses.
Tactile Clicky: Tactile switches provide you with feedback every time you actuate a switch. This is useful for touch-typing because your keyboard will let you know precisely when to stop pressing down. Once actuated, Blue and Green switches make a loud clicking noise. These switches have given mechanical keyboards a reputation for being considerably louder than their rubbery counterparts. In order to mitigate the loud noises, many vendors will add a tiny O-ring to the bottom of a keycap to quiet the click their keyboard makes.
Tactile Non-Clicky: Cherry also makes switches that are specifically designed to give you a tactile feedback bump, but without any of the noise. Clear and Brown switches are immensely popular among the Massdrop community because they feel great to type on, have an easily identifiable actuation point and are incredibly quiet for use in offices and shared spaces.
Another feature that is fundamental to the mechanical keyboard is ergonomics. When you type on a rubber dome keyboard, it is perfectly normal to let your finger effectively "bottom out" and hit the bottom of the keyboard. Basic physics states that every action has an equal opposite reaction. When you "bottom out", your fingers receive repetitive recoil from the act of hitting a flat surface over and over again. Moving to a mechanical switch allows for the key to be actuated at only half the distance, instead of bottoming out each time. This means less force is required with every key press and therefore less fatigue will ensue.
The Many Facets of Keycaps
Arguably the aspect of the community that sets the casual typists apart from the serious enthusiasts is the keycap. In my opinion, being able to customize your keycaps is one of the greatest innovations in the world of keyboards. The ability to personalize a tool to showcase your style is something that makes your keyboard truly your own. The variations of keycaps are endless, but the main differences are found in color, font, and construction. Color and font are relatively straightforward, however, the more complex differences come in the form of construction. Most keycaps are made from injection-molding thermoplastic, which is the process of melting plastic using heat and injecting it under pressure into a steel mold. The most common types of plastic used include ABS and PBT.
ABS plastic, short for "Acrylonitrile Butadiene Styrene" is the most commonly used plastic, mainly due to the fact that the material is less expensive. Although popular, a major shortcoming of ABS plastic is that oil from your fingertips can coat the surface of your keycaps over time.
PBT plastic, short for "polybutylene terephthalate" is one of the most desirable materials for keycaps due to its hardness and durability. These keycaps can last for incredible amounts of time and if you've ever seen a PBT keycap from the 1980's, it will probably look the same as the day it was first used. Its durability comes from its resiliency to heat; however, this resiliency also makes it difficult to mold, which increases manufacturing costs.
Where to Learn More?
In addition to the physical benefits of mechanical keyboards, there is also an incredibly active social community surrounding them, where people post pictures, discuss innovation and even build their own keyboards!