Char cloth is a swatch of fabric made from vegetable fiber (such as linen

Linen

Linen is a textile made from the fibers of the flax plant, Linum usitatissimum. Linen is labor-intensive to manufacture, but when it is made into garments, it is valued for its exceptional coolness and freshness in hot weather....

, cotton

Cotton

Cotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium. The fiber is almost pure cellulose. The botanical purpose of cotton fiber is to aid in seed dispersal....

 or jute

Jute

Jute is a long, soft, shiny vegetable fibre that can be spun into coarse, strong threads. It is produced from plants in the genus Corchorus, which has been classified in the family Tiliaceae, or more recently in Malvaceae....

) that has been converted via pyrolysis

Pyrolysis

Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures without the participation of oxygen. It involves the simultaneous change of chemical composition and physical phase, and is irreversible...

 into a slow-burning fuel of very low ignition temperature. It is capable of being ignited by a single spark

Spark

-Physical sparks:* Spark , a small glowing particle or ember* An electric spark, usually with a flash and a sharp noise-Computer science:* SPARK...

 that can in turn be used to ignite a tinder bundle to start a fire

Fire

Fire is the rapid oxidation of a material in the chemical process of combustion, releasing heat, light, and various reaction products. Slower oxidative processes like rusting or digestion are not included by this definition....

. It is sometimes manufactured at home for use as the initial tinder

Tinder

Tinder is easily combustible material used to ignite fires by rudimentary methods. A small fire consisting of tinder is then used to ignite kindling. Anything that can be ignited by a match can be considered tinder; or by more rigorous definition, anything that begins to glow under a shower of...

 when cooking or camping and historically usually provided the "tinder" component of a tinderbox

Tinderbox

A tinderbox is a small container containing flint, firesteel, and tinder , used together to help kindle a fire....

.

With even the smallest spark, the charcloth will catch light. For this reason, they are commonly used with a flint and steel.