A reel is an object around which lengths of another material (usually long and flexible) are wound for storage. Generally a reel has a cylindrical core and walls on the sides to retain the material wound around the core. In some cases the core is hollow, although other items may be mounted on it, and grips may exist for mechanically turning the reel.

The size of the core is dependent on several factors. A smaller core will obviously allow more material to be stored in a given space. However there is a limit to how tightly the stored material can be wound without damaging it and this limits how small the core can be.

Other issues affecting the core size include:

• Mechanical strength of the core (especially with large reels)
• Acceptable turning speed (for a given rate of material moving on or off the reel a smaller core will mean that an almost empty reel has to turn faster)
• any functional requirements of the core e.g.
  • For a reel that must be mechanically turned the size of the grips that mount it on the mechanical turning device.
  • The size of the mountings needed to support the core during unwinding.
  • Anything mounted on the core (e.g. the sockets on an extension reel)

With material such as photographic film that is flat and long but is relatively wide, the material generally is stored in successive single layers. In cases where the material is more uniform in cross-section (for example, a cable), the material may be safely wound around a reel that is wider than its width. In this case, several windings are needed to create a layer on the reel.

Uses

• A fishing reel is used on a fishing rod to wind the fishing line up.
• Most rope and cable is supplied on reels

Motion Picture Terminology

A so-called "two-reeler" would have run about 20-24 minutes since the actual short film shipped to a movie theater for exhibition may have had slightly less (but rarely more) than 1000 feet on it.

The "reel" was established as a standard measurement because of considerations in printing motion picture film at a film laboratory, for shipping (especially the film case sizes) and for the size of the physical film magazine attached to the motion picture projector. Had it not been standardized (at 1000 feet of 35 mm film) there would have been many difficulties in the manufacture of the related equipment. A 16 mm "reel" is 400 feet. It runs, at sound speed, approximately the same amount of time (11-12 minutes) as a 1000 foot 35 mm reel.

A Split Reel is a motion picture film reel in two halves that, when assembled, hold a specific length of motion picture film that has been wound on a plastic core. Using a split reel allows film to be shipped or handled in a lighter and smaller form than film would on a "fixed" reel. In silent film terminology, two films on one reel.

A Reel, sometimes called a demo reel, can also be referring to a collection of works by an individual, an artist. A collage of your best work. Used as a tool to promote your skill and talent. Like artists have portfolios, persons in film/video whether it be acting, directing, cinematography, editing, motion graphics, or animation have reels. Mechanical engineering