A highlighter is a felt-tip

Marker pen

thumb|MarkerA marker pen, marking pen, felt-tip pen, flow or marker, is a pen which has its own ink-source, and usually a tip made of a porous, pressed fibres; such as felt or nylon.-Permanent marker:...

 pen which is used to draw attention to sections of documents by marking them with a vivid, translucent colour.
A typical highlighter is fluorescent yellow, coloured with pyranine

Pyranine

Pyranine is a hydrophilic, pH-sensitive fluorescent dye from the group of chemicals known as arylsulfonates. Pyranine is soluble in water and has applications as a coloring agent, biological stain, optical detecting reagent, and a pH indicator. One example would be the measurement of intracellular pH...

.

History

In 1962, the modern felt-tip pen was invented in Japan by Yukio Horie. A highlighter is a felt-tip pen filled with transparent fluorescent ink. Avery Dennison Corporation invented and trademarked the name Hi-Liter. The new writing tool became popular and was called highlighter.

Styles

Many highlighters come in bright, often fluorescent colours. Being fluorescent, highlighter ink will glow under a black light

Black light

A black light, also referred to as a UV light, ultraviolet light, or Wood's lamp, is a lamp that emits ultraviolet radiation in the long-wave range, and little visible light...

. The most common colour for highlighters is yellow, but they are also found in pink

Pink

Pink is a mixture of red and white. Commonly used for Valentine's Day and Easter, pink is sometimes referred to as "the color of love." The use of the word for the color known today as pink was first recorded in the late 17th century....

, blue

Blue

Blue is a colour, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 440–490 nm. It is considered one of the additive primary colours. On the HSV Colour Wheel, the complement of blue is yellow; that is, a colour corresponding to an equal...

, green

Green

Green is a color, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 520–570 nanometres. In the subtractive color system, it is not a primary color, but is created out of a mixture of yellow and blue, or yellow and cyan; it is considered...

, orange

Orange (colour)

The colour orange occurs between red and yellow in the visible spectrum at a wavelength of about 585–620 nm, and has a hue of 30° in HSV colour space. It is numerically halfway between red and yellow in a gamma-compressed RGB colour space, the expression of which is the RGB colour wheel. The...

, and purple

Purple

Purple is a range of hues of color occurring between red and blue, and is classified as a secondary color as the colors are required to create the shade....

 varieties. Red highlighters can be purchased along with a green translucent sheet used to hide the highlighted material. This product is sold in Japan and some other countries, and can also be bought online. Some yellow

Yellow

Yellow is the color evoked by light that stimulates both the L and M cone cells of the retina about equally, with no significant stimulation of the S cone cells. Light with a wavelength of 570–590 nm is yellow, as is light with a suitable mixture of red and green...

 highlighters may look greenish in colour to the naked eye.

Highlighters are available in multiple forms including ones with a retractable felt tip or ones which have an eraser on the opposite end of the felt tip. Other types of highlighters include the "trilighter," a triangularly-shaped pen with a different-coloured tip at each corner, and ones that are stackable.

Dry highlighters (occasionally called "dry line highlighters") are highlighters that, instead of having a felt tip, have applicators that apply a strip of highlighter tape similar to audio cassette tape. Unlike standard highlighters, they are easily erasable. They are to be distinguished from "dry mark highlighters", which are sometimes advertised as being useful for highlighting books with very thin pages.

Other uses

• Artist
  Artist
  An artist is a person engaged in one or more of any of a broad spectrum of activities related to creating art, practicing the arts and/or demonstrating an art. The common usage in both everyday speech and academic discourse is a practitioner in the visual arts only...
  
  s have used highlighters (including erasable highlighters), either alone or in conjunction with other media, to create drawing
  Drawing
  Drawing is a form of visual art that makes use of any number of drawing instruments to mark a two-dimensional medium. Common instruments include graphite pencils, pen and ink, inked brushes, wax color pencils, crayons, charcoal, chalk, pastels, markers, styluses, and various metals .An artist who...
  
  s.
• Some word processing software can simulate highlighting by using a technique similar to reverse video
  Reverse video
  Reverse video is a computer display technique whereby the background and text colour values are inverted. On older computers, displays were usually configured to display white text on a black background by default. For emphasis, one swapped the color scheme to bright background with dark text...
  
   on some terminals. Similar to this is the program Web Highlighter, which allows users to "attach highlighting, notes, and links to any Web page viewed with Microsoft Internet Explorer 4.0 or later."