Embedded fonts

Embedded fonts are typefaces packaged inside the PDF itself, rather than relied upon from whatever computer happens to open the file. This is the mechanism behind one of PDF's core promises: the document looks the same everywhere.

When a font is not embedded, the viewer substitutes the closest one it can find, which shifts spacing, breaks layouts, and can swap your carefully chosen typeface for a generic fallback. By embedding the font, the PDF carries the exact glyphs it needs, so the text renders identically on a machine that has never seen that typeface. Fonts can be embedded fully or as subsets that include only the characters actually used, which keeps file size down.

This is why standards for archiving (PDF/A) and printing (PDF/X) require font embedding. If a document absolutely must look right, on screen, in print, or years from now, embedded fonts are what guarantee it.