A pen (Latin pinna, feather) is a long, thin, rounded device used to apply ink to a surface for the purpose of writing or drawing, usually paper. There are several different types, including ballpoint, rollerball, fountain, and felt-tip. Historically, reed pens, quill pens, and dip pens were used. Modern-day pens come in a variety of colors and assortments. The most common contain black or blue ink.
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Types

The main modern types of pens can be categorized by the kind of writing tip or point:
A letter written on paper with a rollerball pen, and the tip of that pen

* A ballpoint pen dispenses viscous oil-based ink by rolling a small hard sphere, usually 0.7–1.2 mm and made of brass, steel or tungsten carbide.[1] The ink dries almost immediately on contact with paper. This type of pen is generally inexpensive and reliable. It has replaced the fountain pen as the most popular tool for everyday writing.
* A rollerball pen dispenses a water-based liquid or gel ink through a ball tip similar to that of a ballpoint pen. The less-viscous ink is more easily absorbed by paper than oil-based ink, and the pen moves more easily across a writing surface. The rollerball pen was initially designed to combine the convenience of a ballpoint pen with the smooth “wet ink” effect of a fountain pen. Gel inks are available in a range of colors, including metallic paint colors and glitter effects.
* A fountain pen uses water-based liquid ink delivered through a nib. The ink flows from a reservoir through a “feed” to the nib, then through the nib, due to capillary action and gravity. The nib has no moving parts and delivers ink through a thin slit to the writing surface. A fountain pen reservoir can be refillable or disposable, this disposable type being an ink cartridge. A pen with a refillable reservoir may have a mechanism, such as a piston, to draw ink from a bottle through the nib, or it may require refilling with an eyedropper. Refillable reservoirs are available for some pens designed to use disposable cartridges.

A fountain pen

* A marker, or felt-tip pen, has a porous tip of fibrous material. The smallest, finest-tipped markers are used for writing on paper. Medium-tip markers are often used by children for coloring. Larger markers are used for writing on other surfaces such as corrugated boxes, whiteboards and for chalkboards, often called “liquid chalk” or “chalkboard markers.” Markers with wide tips and bright but transparent ink, called highlighters, are used to mark existing text. Markers designed for children or for temporary writing (as with a whiteboard or overhead projector) typically use non-permanent inks. Large markers used to label shipping cases or other packages are usually permanent markers.
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Historic types

These historic types of pens are no longer in common use:

* A dip pen (or nib pen) consists of a metal nib with capillary channels, like that of a fountain pen, mounted on a handle or holder, often made of wood. A dip pen usually has no ink reservoir and must be repeatedly recharged with ink while drawing or writing. The dip pen has certain advantages over a fountain pen. It can use waterproof pigmented (particle-and-binder-based) inks, such as so-called India ink, drawing ink, or acrylic inks, which would destroy a fountain pen by clogging, as well as the traditional iron gall ink, which can cause corrosion in a fountain pen. Dip pens are now mainly used in illustration, calligraphy, and comics (notably manga).
* A quill is a pen made from a flight feather of a large bird, most often a goose. Quills were used as instruments for writing with ink before the metal dip pen, the fountain pen, and eventually the ballpoint pen came into use. The shaft of the feather acts as an ink reservoir, and ink flows to the tip by capillary action. Quill pens were used in medieval times to write on parchment or paper. The quill eventually replaced the reed pen.
* A reed pen is cut from a reed or bamboo, with a slit in a narrow tip. Its mechanism is essentially similar to that of a quill. The reed pen has almost disappeared but it is still used by young school going students in some parts of Pakistan, who learn to write with them on small timber boards known as “Takhti”. Popular belief has it that writing with a reed pen improves handwriting.
* The ink brush is the traditional writing implement in East Asian calligraphy. The body of the brush can be made from either bamboo, or rarer materials such as red sandalwood, glass, ivory, silver, and gold. The head of the brush can be made from the hair (or feathers) of a wide variety of animals, including the weasel, rabbit, deer, chicken, duck, goat, pig, tiger, etc. There is also a tradition in both China and Japan of making a brush using the hair of a newborn, as a once-in-a-lifetime souvenir for the child. This practice is associated with the legend of an ancient Chinese scholar who scored first in the Imperial examinations by using such a personalized brush. Calligraphy brushes are widely considered an extension of the calligrapher’s arm. Today, calligraphy may also be done using a pen, but pen calligraphy does not enjoy the same prestige as traditional brush calligraphy.

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