A monochrome raster image format. Each dot (pixel) is either filled (black, on, 1) or not filled (white, off, 0), there are no gray tones (halftones, grayscales).
The name Bitmap comes from the 1:1 mapping of each pixel to a dot/pixel on the screen.
Bleed is printing that goes beyond the edge of where the sheet will be trimmed. Bleed marks belong to the larger category of Print Marks. They represent a special form of a cutting mark.
See Page Geometry