Parachute cord (also paracord or 550 cord when referring to type-III paracord) is a lightweight nylon kernmantle rope originally used in the suspension lines of US parachutes during World War II. Once in the field, paratroopers found this cord useful for many other tasks. It is now used as a general purpose utility cord by both military personnel and civilians. This versatile cord was even used by astronauts during the 82nd Space Shuttle mission to repair the Hubble Space Telescope.
The braided sheath has a high number of interwoven strands for its size, giving it a relatively smooth texture. The all-nylon construction makes paracord fairly elastic; depending on the application this can be either an asset or a liability.
Current technical standards for the manufacture of cord for use in parachutes are published by the Parachute Industry Association. The US military MIL-C-5040H standard required the material to be nylon. Similar styles of cord are manufactured with other materials such as polyester.
Paracord types and size:
There are several different types of paracord:
Read more about it at http://www.paracordplanet.com/What-Paracord-To-Buy.html
A page in Norwegian: https://www.paracord.no/blog/fakta-om-paracord
Image is from www.paracordplanet.com