Ink is a liquid that is used to write, draw, print, or make marks. The word ink is from Latin and means "colored water". Ink is used in pens, in some computer printers, and in printing presses. In some countries, people write by using ink and brushes. People usually write or print using black ink, but ink can be any color. The first ink was used in Egypt about 2600 BC.

The first inks were carbon inks, made from soot, which is 80% carbon, water and gum arabic. Red ink would need iron oxide (such as haematite) from ground rocks instead of soot. Later, in Europe, people used iron gall ink. This is the kind of ink Johann Sebastian Bach and Leonardo da Vinci used. Now ink colours are produced by man-made dyes.

A disadvantage of many kinds of ink is that they may smudge when wet, spoiling the picture or writing. If water-based ink is used, the writing situation needs to be stable, with the writer seated at a table. Ink in a ballpoint pen (biro) is a kind of gel. It is held in a thin long cylinder (tube) inside the pen. The ink does not fall out of the cylinder as it sticks to the sides of the tube. Therefore, ballpoint pens can be used in a wider range of circumstances compared to water-based inks.

== References ==

• Martín-Gil, J.; Ramos-Sánchez, M.C.; Martín-Gil, F.J.; José-Yacamán, M. (2006), "Chemical composition of a fountain pen ink", Journal of Chemical Education, 83 (10): 1476–1478, doi:10.1021/ed083p1476.

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