Hinge in the context of "Lever"

A diptych (/ˈdɪptɪk/, DIP-tick) is any object with two flat plates which form a pair, often attached by a hinge. For example, the standard notebook and school exercise book of the ancient world was a diptych consisting of a pair of such plates that contained a recessed space filled with wax. Writing was accomplished by scratching the wax surface with a stylus. When the notes were no longer needed, the wax could be slightly heated and then smoothed to allow reuse. Ordinary versions had wooden frames, but more luxurious diptychs were crafted with more expensive materials.

A pin is a device, typically pointed, used for fastening objects or fabrics together. Pins can have the following sorts of body:

• a shaft of a rigid inflexible material meant to be inserted in a slot, groove, or hole (as with pivots, hinges, and jigs)
• a shaft connected to a head and ending in a sharp tip meant to pierce one or more pieces of soft materials like cloth or paper (the straight or push pin)
• a single strip of a rigid but flexible material (e.g. a wire) whose length has been folded into parallel prongs in such fashion that the middle length of each curves towards the other so that, when anything is inserted between them, they act as a clamp (e.g. the bobby pin)
• two strips of a rigid material bound together by a spring at one end so that, when the spring held open, one can insert some material between the prongs at the other end that, the spring allowed to close, then clamp the inserted material.

According to their function, pins can be made of metals (e.g. steel, copper, or brass), wood, or plastic.

A door is a hinged or otherwise movable barrier that allows ingress (entry) into and egress (exit) from an enclosure. The created opening in the wall is a doorway or portal. A door's essential and primary purpose is to provide security by controlling access to the doorway (portal). Conventionally, it is a panel that fits into the doorway of a building, room, or vehicle. Doors are generally made of a material suited to the door's task. They are commonly attached by hinges, but can move by other means, such as slides or counterbalancing.

The door may be able to move in various ways (at angles away from the doorway/portal, by sliding on a plane parallel to the frame, by folding in angles on a parallel plane, or by spinning along an axis at the center of the frame) to allow or prevent ingress or egress. In most cases, a door's interior matches its exterior side. But in other cases (e.g., a vehicle door) the two sides are radically different.

A polyptych (/ˈpɒlɪptɪk/ POL-ip-tik; Greek: poly- "many" and ptychē "fold") is a work of art (usually a panel painting) which is divided into sections, or panels. Some definitions restrict "polyptych" to works with more than three sections: a diptych is a two-part work of art; a triptych is a three-part work; a tetraptych or quadriptych has four parts; a pentaptych has five parts. The great majority of historical examples are paintings with religious subjects, but in the 20th century the format became popular again for portraits and other subjects, in painting, photography, and other media.

Historically, polyptychs were panel paintings that typically displayed one "central" or "main" panel that was usually the largest; the other panels are called "side" panels, or if hinged, "wings". Folding forms were much more common north of the Alps. Sometimes, as evident in the Ghent Altarpiece and Isenheim Altarpiece, the hinged panels can be varied in arrangement to show different "views" or "openings" in the piece, because the wing panels are painted with images on both sides. The wings were usually kept folded shut, showing the "closed" view, except on Sundays or feast-days, or if visitors paid the sacristan for a sight of the "open" view. The upper panels often depict static scenes, while the lower register, the predella, often depict small narrative scenes.

In discrete geometry and mechanics, structural rigidity is a combinatorial theory for predicting the flexibility of ensembles formed by rigid bodies connected by flexible linkages or hinges.

Handcuffs are restraint devices designed to secure an individual's wrists in proximity to each other. They comprise two parts, linked together by a chain, a hinge, or rigid bar. Each cuff has a rotating arm which engages with a ratchet that prevents it from being opened once closed around a person's wrist. Without a key, handcuffs cannot be removed without specialist knowledge, and a handcuffed person cannot move their wrists more than a few centimetres or inches apart, making many tasks difficult or impossible.

Handcuffs are frequently used by law enforcement agencies worldwide to prevent suspected criminals from escaping from police custody.

A casement window is a window that is attached to its frame by one or more hinges at the side. They are used singly or in pairs within a common frame, in which case they are hinged on the outside. Casement windows are often held open using a casement stay. Windows hinged at the top are referred to as awning windows, and ones hinged at the bottom are called hoppers.

Clamshell design is a form factor commonly used in the design of electronic devices and other manufactured objects. It is inspired by the morphology of the clam. The form factor has been applied to handheld game consoles, mobile phones (where it is often called a "flip phone"), and especially laptop computers. Clamshell devices are usually made of two sections connected by a hinge, each section containing either a flat panel display or an alphanumeric keyboard/keypad, which can fold into contact together like a bivalve shell.

Generally speaking, the interface components such as keys and display are kept inside the closed clamshell, protecting them from damage and unintentional use while also making the device shorter or narrower so it is easier to carry around. In many cases, opening the clamshell offers more surface area than when the device is closed, allowing interface components to be larger and easier to use than on devices which do not flip open. A disadvantage of the clamshell design is the connecting hinge, which is prone to fatigue or failure.