: Screen readers can "read" this invisible layer, making scanned image-based PDFs accessible to visually impaired users. Where to Find a Glyphless Font Free Download

Often only contains .notdef and .null glyphs to minimize data. How to Use a Glyphless Font

: Standard fonts require embedding full glyph definitions, which can significantly increase file sizes. A glyphless font only includes basic metrics (like height and width), keeping the file size to a few kilobytes.

: You can install it on your OS like a normal font by double-clicking the file, though you won't see characters in a word processor.

Contains width and height data used for text selection boxes.

: Use it within libraries (like pdf-lib or reportlab ) to overlay text on images. By setting the text color to transparent or using a glyphless font, users can "select" and "copy" text from the image layer without seeing the overlay. Publisher and Text import in PDF - and Glyphless Font

: When a document is OCR’d (Optical Character Recognition), a glyphless font is used to create an invisible text layer over the background image. This allows you to search for and highlight text that technically doesn't "exist" as visible characters on the page.

TrueType (.ttf) is the most standard for these "dummy" files.