font

In more detail

A font file is not the text. It is a set of drawings — one for the A, one for the a, one for the comma, one for the euro sign — together with how wide each of them is and how far apart two of them sit when they meet. The document holds the words; the font says what they look like.

A family also comes in weights and slants — the regular, the bold, the italic — and each of those is a file of its own, which is why a document set in three of them carries three.

What it does on a real document

A PDF carries inside itself the fonts it is set in. That is the whole reason a document opens looking the same on a machine that has never heard of the font it was written in, and it is the first thing a printing works asks for before accepting a job. Leave them out and the reading software at the far end puts another font in their place: the lines change length, and the layout moves.

Carrying one whole would be wasteful, so only the letters actually drawn travel, which is what a lightened font is. The fourteen faces all reading software has to draw for itself are the exception: a document asking for one of them carries no font at all, and pays for it in the alphabets it can no longer write.

Where it comes from, and why

Type was metal for four centuries, and a font was a case of it: one piece of lead per letter, cast at one size, bought by the pound. The word crossed to software with its meaning intact — a complete set of shapes, owned and paid for — which is why putting one inside a document you hand to a customer is still a question for a lawyer.

See it on a finished document

Fonts embedded in the file A page that carries no font The page that goes further on this word