A writing implement or writing instrument is an object used to produce writing. Most of these items can be also used for other functions such as painting, drawing and technical drawing, but writing instruments generally have the unique requirement to create a smooth, controllable line.
The ancient Sumerians and their successor cultures, such as the Babylonians, produced their cuneiform writing by pressing a triangular stylus into soft clay tablets, creating characteristic wedge-shaped marks. The clay tablets were then baked to harden them and permanently preserve the marks.
Several other ancient cultures such as Mycenaean Greece also inscribed their records into clay tablets but did not routinely bake them; much of the Linear B corpus from Minoan Crete was accidentally preserved by a catastrophic fire which hard-baked those tablets. The Romans used lead styli with wax tablets which could be "erased" by rubbing the beeswax surface smooth again.
Words and names are still commonly inscribed into commemorative objects, such as the engraved winners' names on the silver Stanley Cup or the Gettysburg Address carved into the stone wall of the Lincoln Memorial, but the requisite tools are not exclusively considered to be writing instruments.
White chalk has been traditionally used in schoolrooms to write on a main blackboard at the front of the room. In the 19th century, and indeed well into the 20th century, when paper was less readily available, individual students also wrote with chalk on their own small slates.
Both pencils and chalk exist in variants which can create marks in other colors, but colored pencils and colored chalk are generally considered to be art supplies rather than writing instruments. Similarly, although very young children may use colorful wax crayons to write words into their pictures, writing is not considered to be the primary use of crayons.
A wax pencil resembles both a crayon and a pencil in that it contains a brightly colored wax core within a protective paper casing, but its proportions are closer to that of a standard pencil. Wax pencils are primarily used to write onto nonporous surfaces such as porcelain or glass.
Normal pencils, chalk, and crayons all share the characteristic that they cannot "run out". The useful life of these implements is closely linked to their physical existence. However, specialized accessories such as pencil sharpeners may be required to reshape the working end of the pigment core or to remove the outer casing from around the tip.
Reed pens were used by the ancient Egyptians to write on papyrus. Quill pens were standard in Europe and the United States up through the 18th and 19h centuries, and are still used in various contexts, such as calligraphy and formal settings such as major bank transactions. The most common quills were taken from the wings of geese or ravens, although the feathers of swans and peacocks were sometimes favored for prestige.
A dip pen has a steel nib - the pen proper - and a pen-holder. Dip pens are very versatile, as the pen-holder can accommodate a wide variety of nibs that are specialized for different purposes-- copperplate writing, mapping pens, and five-pointed nibs for drawing music staves-- and can be used with most types of ink, some of which are incompatible with other types of pen. Automatic pens are a category of dip pen, in which the nib is in two parts and can hold a larger quantity of ink. However, like all of its precursors, the steel-nibbed dip pens had a limited ink reservoir and a tendency to drip inkblots on the page.
Only certain types of ink can be used in a fountain pen, to avoid clogging up the nib unit mechanism. Although the larger reservoir of fountain pens requires less frequent ink replenishment, the ink may inconveniently spill out in certain contexts to stain the paper, fingers, or clothing of an unwary writer. Differences in air pressure may cause spectacular effects when travelling by airplane.
These types include the ballpoint pen (often called a biro in many Commonwealth countries) and the felt tip pen. Both of these have subtypes which are popularly called by their own specific names, usually based on the type of their ink, such as the fluorescent highlighter, the rollerball pen, and the gel pen.
A brush differs from a pen in that instead of a rigid nib, the brush is tipped with soft bristles. The bristles are gently swept across the paper with just enough pressure to allow ink to wick onto the surface, rather than mashing down the brush to the extent of substantial friction resistance. Although pens with semi-flexible nibs and liquid ink can also vary their stroke width depending on the degree of applied pressure, their variation range is far less obvious.
Traditionally, brushes have been loaded with ink by dipping the bristles into an external pool of ink on an inkstone, analogous to a traditional dip pen with an inkwell. Some companies now make "brush pens" which in that regard resemble a fountain pen, with an internal ink reservoir built into the handle which can be refilled with preloaded cartridges or a bottle-fill converter.