BDf

BDF stands for several phrases across different fields, but in computing it most commonly refers to the Bitmap Distribution Format, a font file format historically used by the X Window System.

Bitmap Distribution Format fonts describe the appearance of each glyph as a monochrome bitmap, together with metadata about the font such as family name, size, and character metrics. BDF files are plain text, which makes them relatively easy to inspect and edit by hand. A typical BDF file includes sections such as FONT, SIZE, and FONTBOUNDINGBOX, followed by a sequence of glyph blocks. Each glyph begins with STARTCHAR and ends with ENDCHAR and contains entries like ENCODING (the code point), DWIDTH and SWIDTH (horizontal metrics), BBX (bounding box), and a BITMAP section that encodes the bitmap data in hexadecimal.

In practice, BDF played a key role in early X11 environments, where bitmap fonts were rendered directly by the display server. Tools exist to convert between formats, most notably bdftopcf, which compiles a BDF font into PCF (a compact binary font format used by X). As scalable font formats such as TrueType and OpenType became predominant, the use of BDF declined for general-purpose text rendering, though it remains relevant for font development, embedded systems, and environments requiring simple, human-readable font representations.

The acronym BDF can denote other terms in non-technical contexts, depending on field and locale. When encountering the term, the intended meaning usually depends on surrounding content or explicit definition within a given domain.