Highlighter is a variant of felt-tip pen with water-based ink that is used for marking of text. It uses vivid, translucent color that makes text stand out more without obscuring it. It is very popular with students who use them to mark important parts of text for easier learning.
The first two marker pens appeared in 1910 and 1926, respectively and were not sold commercially. The first one was Lee Newman’s felt-tip marker and second one Benjamin Paskach’s "fountain paintbrush" - a sponge-tipped handle with colors inside. Walter J. De Groft made a "marking pen" in 1944 and would later sell it to become a “Sharpie” pen in 1964. But before Sharpie appeared Sidney Rosenthal invented and started selling in 1953 a “Magic Marker”. The first predecessor of a highlighter was invented by a Japanese inventor Yukio Horie of the Tokyo Stationery Company, who developed in 1962 the first felt-tip pen that used water-based ink. It was not made to highlight texts, but it inspired Carter’s Ink Company to, in 1963, start manufacturing similar water-based Marker with translucent ink. It was sold under the name Hi-Liter, and it worked on capillary action.
In 1978, Dennison Company, today’s Avery Dennison Corporation bought Carter’s Ink and started making highlighters with fluorescent colors. In the 1980s, felt the tip was replaced with polyethylene beads molded into porous heads. They make less sound when used (felt with ink squeaks when used) and ink flows through them more smoothly. At first (as half of the commercial products), highlighters were not embraced by people who preferred pens. Because of that, manufacturers started selling dual highlighter/pen which helped to break the ice.
Before highlighters, students marked important parts of the texts they were learning by underlining the text or by leaving bookmarks at the important places. With highlighters, marked parts become more visible and easier to find. Highlighters have casings that are clickable or with caps that prevent highlighter from drying. They are also built in different shapes and colors. Some 85% of all bought highlighters are in yellow and pink color, but there are also highlighters that mark in orange, red, purple, blue, and green. Yellow is the most popular because it is the lightest color and when a text that is highlighted in yellow is photocopied, yellow is not seen on a copy. There are also, so-called, “trilighter” highlighters - triangularly-shaped pens with tips of different colors at each corner. Some highlighters have a wax-like quality and leave marks similar to an oil pastel. Special variant of a highlighter - "dry highlighter" or "dry line highlighter" applies a thin strip of highlighter tape instead of ink mark on the surface. They are much easier to remove than standard highlighter marks. Special markers are made for Bibles that don’t bleed through the thin paper from which are most Bibles made.
Today, even computer word processors and e-book readers have the highlighting option under the influence of highlighter markers. That shows how important we consider marking of texts nowadays and how much highlighters changed and made text processing easier.