What do we call a medieval shield symbol used to identify a family?

The story behind the answer

Because medieval warfare and tournaments hid faces behind visors, Europe developed heraldry: unique, inheritable designs displayed on shields and banners to identify individuals and lineages. These armorial bearings followed strict rules of color (tinctures), symbols (charges), and patterns, and were recorded by heralds to prevent duplication. Families displayed them on shields, seals, and later on buildings and documents, turning identity into a visual code.

Common confusions: a “crest” is only the figure atop a helmet, not the whole design; a “heraldic badge” is a simpler emblem worn by retainers; “house sigil” is a modern fantasy term. The full achievement could include shield, helm, crest, mantling, supporters, and motto—an enduring system that still marks institutions and cities today.