Blackwork, sometimes historically termed Spanish blackwork, is a form of embroidery generally worked in black thread, although other colours are also used on occasion, as in scarletwork, where the embroidery is worked in red thread.^[1] Most strongly associated with Tudor period England, blackwork typically, though not always, takes the form of a counted-thread embroidery, where the warp and weft yarns of a fabric are counted for the length of each stitch, producing uniform-length stitches and a precise pattern on an even-weave fabric. Blackwork may also take the form of free-stitch embroidery, where the yarns of a fabric are not counted while sewing.

Traditionally, blackwork is worked in silk thread on white or off-white linen or cotton fabric. Sometimes metallic threads or coloured threads are used for accents.