glyph

What the word means

You type a letter. What lands on the page is a drawing of that letter, and every typeface draws it differently. The letter is the idea; the glyph is the shape.

The two do not always match one for one. In some typefaces an f and an i side by side are drawn as a single joined shape: two letters, one glyph. In Arabic a letter is drawn differently depending on what stands next to it: one letter, four glyphs.

What it does on a real document

Inside a PDF the page does not name letters. It names drawings, by number, in the typeface the file carries. That is why a page can look perfect and give nothing when you copy it: the file drew shapes and never said which letters they were.

The engine writes the missing sentence beside the drawings — this shape number is that letter — so selecting a paragraph and pasting it elsewhere gives the words back. Search engines and reading aids need exactly the same sentence.

Where it comes from, and why

The word comes from the Greek for a carving. Printers borrowed it for the shape cut into a piece of metal type, and kept it when the metal went away.

The distinction became a working necessity when computers had to handle every writing system in the world. The list of letters, which is the same everywhere, was separated from the drawings, which belong to each typeface. That separation is what lets one document mix alphabets no single foundry ever cut together.

See it on a finished document

Letters you draw yourself One letter each, in one file The rules behind this word, and the texts they are read from