Bitmap

1. A graphic file format with file extensions of *.bmp or *.dib (device-independent bitmap) used in Microsoft Windows and OS/2. Bitmap images today are often saved in either 4-bit (16 color), 9-bit (256 color), 16-bit (65,536 color), and 24-bit (16.7 million color). Because bitmap images are uncompressed and require much more disk space when compared to comparable images such as GIF and JPEG bmp and dib images are not commonly used outside of the Windows environment.
2. A bitmap is also used to describe raster or bitmapped image formats.

Also see: Bitmap font, Object-oriented graphics, PNG, Raster, Video definitions