Mark Master is a degree of the York Rite's Chapter body, the Royal Arch Masons, conferred on Master Masons who continue their Masonic membership into the York Rite. It is the first of the Chapter's sequence, preceding Past Master, Most Excellent Master and Royal Arch Mason, the degree that completes the Chapter.
The degree's name and central theme reach back to an operative tradition distinct from the Craft degrees beneath it: stonemasons' guilds required each working mason to adopt a personal mark, cut into finished stone as a record of whose work it was, a practice attested in the archaeology and documentary record of medieval and early modern building trades well before speculative Freemasonry existed. The York Rite's Mark Master degree draws its symbolism from that guild custom rather than from the biblical Temple imagery that dominates the Chapter's later degrees.
The York Rite as a whole is organized into three bodies, Chapter, Council and Commandery, each conferring its own small sequence of further degrees on Master Masons who choose to continue beyond the basic Craft system. Mark Master, as the Chapter's opening degree, is the first point at which a Mason's York Rite membership diverges from the Ancient and Accepted Scottish Rite's parallel but separately organized sequence of appendant degrees.