Half-blood is the term commonly given to wizards and witches who have both Muggle/Muggle-born and wizard ancestry. By the late 20th century, half-bloods were the most common type of magical person, as the wizarding population would have become extinct had they not inter-married with Muggles and Muggle-borns. It should be noted that any wizard who is not either Pure-blood or Muggle-born is considered a Half-blood, even if they have two wizard parents; they need not have exactly half-Muggle/half-wizard heritage.