Mechanical keyboards are made up of many different parts. While fully-assembled keyboards are always an option, sometimes it's fun to build one yourself. If you don't want to solder and assemble a board yourself, fully customizable boards are also an option. Each part of a keyboard can be mixed and matched to build something completely unique to you!
PCB (Printed Circuit Board)
This is the heart and brain of your keyboard! Your circuit board will determine the size and layout of your keyboard. Different circuit boards also offer different possibilities such as reprogrammable key functions, customizable lighting, whether your keyboard is wireless or wired, and sometimes even funky things like sound effects. If your PCB is hot-swappable, that means you can simply plug in and remove switches. Otherwise, you'll need to solder your switches to the circuit board.
Many keyboards also include mounting plates which are placed directly above the PCB. These plates help align the switches with the PCB, protect the PCB, and offer more structure to the keyboard. They come in a variety of materials and finishes. If you opt to use a mounting plate, your switches are considered "plate mounted". If you don't, they are considered "PCB mounted".
Your PCB and mounting plate both fit into an exterior case which serves as the base of the keyboard and protects the sides of the PCB. High-profile cases have sides which rise to the bottom of the keycaps in their resting position. Low-profile cases have sides which end at the top of the mounting plate and allow you to see your switches from the side.
Some keys (like spacebars, enter keys, and shift keys) are larger than other keys but switches only come in one size. To prevent these keys from wobbling or wiggling off their switches, stabilizers are installed to offer the key more support and stability.
Switches are the soul of a mechanical keyboard! When you press down on a switch, the stem pushes down allowing two metal contacts to touch and register a keypress. This moment of contact is called the "actuation point" Switches are generally classified into three main categories by their method of actuation:
Linear switches are smooth all the way down. They don't make much noise and the only way to know when a keystroke has been registered is by watching your screen. They also enable a more rapid pressing of the keys.
Tactile clicky switches provide tactile and audible feedback. Just before the keystroke actuates, there is a moment of extra resistance. By pushing past this "bump", the keystroke actuates and makes a clicking sound.
Tactile non-clicky switches have a "bump" providing tactile feedback but do not make a clicking sound like clicky switches. If you like the feedback of a clicky switch but don't want to annoy coworkers, these are a good choice.
Switches are generally designated by their brand and stem color (ie Cherry MX Reds). Other than the actuation method, switches are defined by factors such as the force needed to actuate each keystroke, the distance until the switch "bottoms out", and which boards and keycaps they are compatible with.
Keycaps are one of the funnest parts of a keyboard! Keycaps are the housings which cover each switch. They come in a variety of different colors, materials, shapes, and offer endless customizability. Whether you want keycaps with all of the Photoshop shortcuts printed on them, keycaps made of wood, or Iron Man themed keycaps, there's likely somewhere to buy or make them.
Accessories & Other Parts
In addition to the key components that make up your keyboard are a number of accessories and tools that can compliment and customize your keyboard. Some are as simple as the cables you use to connect your keyboard to your computer. Others are niche products for serious enthusiasts who like to take apart and lubricate their switches. There are storage trays for your extra switches, dust covers to protect your keyboard when not in use, wrist rests, desk mats, o-rings to make your board more quiet, and more!