Pen is a general name for a writing tool that uses liquid pigment to leave a mark on the surface. This liquid pigment is ink.
History of pens starts in Ancient Egypt where scribes, trying to find replacement for styluses and writing in clay, invented reed pens. These pens were made from a single reed straw that is pointed at one end and with a slit that led the ink to the point and left the mark on the papyrus. This pen was too rigid and its point didn’t last long. Because of that people started using quills - pens made from molted flight feathers of large birds. These pens were also made by making a point at thicker end but feathers were cured before the use and could maintain the point longer. They were popular in the Western World from the 6th to the 19th century until steel pens appeared.
Metal nibs for dip pens were used in Ancient Rome but were not popular until they were mass produced in 19th century. Pens with reservoirs were known since 10th century but were not widely used. In 17th century, inventor Daniel Schwenter made a pen made from two quills that held the ink inside instead of being dipped into inkwell. The first fountain pens appeared in 19th century in France and revolutionized writing because they made much less mess and didn’t have to be dipped in inkwell all the time. End of the 19th century saw also the first ballpoint pen which was, when modernized, even more practical and cheaper than fountain pen. The first fiber or felt-tipped pen was invented in Japan in 1960s and it later developed into marker pen and highlighter which work on the similar principle. After that, in the 1970s, was invented rollerball pen, which is similar to ballpoint pen but uses water-based inks while ballpoint uses oil-based.
Ink is as old as pen and maybe even older. Chinese knew about ink in 23rd century BC. They made plant, animal, and mineral inks and used it for painting on silk and paper. The best ink they used was made from pine sap made from trees that were between 50 and 100 years old. They also made ink from mixture of hide glue, carbon black, lampblack, and bone black pigment which was mixed with pestle and mortar. In India, ink was made since 4th century BC. This ink called “masi” was made from burnt bones, tar, and pitch. Greeks and Romans made ink from soot, glue and water (so called “carbon inks”). They don’t damage the paper they reused on but are not resistant to moist and can smudge. “Iron gall ink” was popular from 5th century to the 19th century and was made from made from iron salts and tannic acids. Only problem with this ink was that it is corrosive and damages the paper it is on. In 12th century Europe, ink was also made from branches of hawthorn which were cut in the spring and left to dry. Then the bark from the branches would be peeled off and left to soak in water for eight days. That water would be boiled until it is thick and black but while boiling, wine would be added to it. That thick and black liquid would be poured in bags and left on sun to dry. When it is dried, wine (again) and iron salt would be mixed with it over fire. Resulting mixture would be ink ready to use.
Together, pen and ink changed the face of the humanity and are regarded because of that as one of the greatest inventions.