A marker pen, fine liner, marking pen, felt-tip pen, felt pen, flow marker, sign pen (in South Korea), vivid (in New Zealand), texta (in Australia), sketch pen (in South Asia) or koki (in South Africa), is a pen which has its own ink source and a tip made of porous, pressed fibers such as felt.
A marker pen consists of a container (glass, aluminum or plastic) and a core of an absorbent material that holds the ink. The upper part of the marker contains the nib that was made in earlier times of a hard felt material, and a cap to prevent the marker from drying out.
Until the early 1990s, the most common solvents that were used for the ink in permanent markers were toluene and xylene. These two substances are both harmful and characterized by a very strong smell. Today, the ink is usually made on the basis of alcohols (e.g. 1-Propanol, 1-butanol, diacetone alcohol and cresols).
Markers may be waterproof, dry-erase, wet-erase (e.g. transparency markers), or permanent.
Lee Newman patented a felt-tipped marking pen in 1910. In 1926, Benjamin Paskach patented a "fountain paintbrush", as he called it, which consisted of a sponge-tipped handle containing various paint colors. Markers of this sort began to be popularized with the sale of Sidney Rosenthal's Magic Marker (1953), which consisted of a glass tube of ink with a felt wick. By 1958, use of felt-tipped markers was commonplace for a variety of applications such as lettering, labeling, and creating posters. The year 1962 brought the development of the modern fiber-tipped pen (in contrast to the marker, which generally has a thicker point) by Yukio Horie of the Tokyo Stationery Company (which later became Pentel).
In 1993 the Copic Sketch markers were released, popularising markers for professional illustration.
The marker reservoir, which holds the ink, is formed from polyester. The "felt" used for the tip is usually made of highly compressed synthetic fibers or porous ceramics. Toluol and xylol were used as solvents for the dye and are still used for the indelible ink in permanent markers.