An ink is composed of pigment and solvent. Pigment gives ink its color and comes from a variety of sources with nitrogen-containing compounds, commonly known as dyes. Solvent is derived from soybean oil, linseed oil or a heavy petroleum distillate.
Ink in historical times was derived from fruit juices, blood from shellfish or tannin. The first ink has been traced back to Egypt over 4,500 years ago. As of 2014, there are two main categories of ink: printing ink and writing ink. Printing ink is made for personal or commercial equipment, and writing ink is used in pens. The ink industry is valued at over $10 billion.