Upper - The part of the shoe that covers the entire foot, and is connected to the outsole. They are often composed of synthetic leathers, and some may even include mesh panels for improved breathability.
Last - A three-dimensional foot-shapped model that is used when designing shoes. The size and shape of an upper is determined by the last that the manufacturer uses.
Insole (or Footbed) - The layer of material that sits on the bottom of the inside of the shoe. This is the part that your foot rests on. The insole offers comfortability and some even offer enhanced arch support.
Midsole - The layer of material between the insole and the outsole that can help provide additional shock absorption. Not all shoes have midsoles.
Outsole - The bottom part of the shoe that comes in contact with the pedals. They are most often composed of carbon or nylon, and have varying levels of grip depending on the type of shoe.
Toe Spikes - Some mountian bike shoes have a spot for toe spikes. Toe spikes can help give you improved traction over loose or muddy terrain. They are most useful for people who may have to hop of the bike at some points and carry their bike, like cyclocross racers.
Hook and Loop - A type of closure featuring a strap with a material that adheres to itself, similar to Velcro® material.
Ratchet - A two-part closure that consists of a ratcheting buckle and a strap that clicks into position, allowing for quick adjustments while riding.
Rotary Ratchet - A two-part closure that consists of a mechanical dial and a thin wire that is run across the top of the shoe, similar to laces. It allows for even quicker and easier adjustments while riding. Boa closures and Sidi's Tecno 3 Buckles are two types of rotary ratchets.
Clipless Pedals - A three-part system that requires bike shoes, cleats, and pedals that are all compatible with each other. With the cleats attached to the outsole of the shoes, you are able to clip-in to the pedals to enhance performance.
Cleats - The component of a clipless pedal system that get's attached to the bottom of the shoe. Most cleats are either 2-bolt or 3-bolt.
Float - The amount of lateral movement you have when cleats are clipped-in. Many pedals today have some degree of float to allow you to futher adjust your pedalling position, to improve performance and avoid injury. Most 2-bolt pedals offer between 0° and 6° of float, while road shoes typically have between 0° and 9° of float.
Release Angle - The required angle you have to twist you foot to release from a clipless pedal. Some cleats allow for adjustable release tension by switching the foot you use for a cleat.
Platform Pedals - The most basic pedal system, compatible with any type of shoe. Platform pedals do not allow you to clip-in, so the cleat compatibility does not matter. However, purchasing bike shoes, especially shoes designed specifically with platform pedals in mind, will help enhance your pedalling efficiency.