Muggle-born is the term applied to wizards and witches who come from non-magical families. According to Rowling, the average Hogwarts annual intake for Muggle-borns is 25%. Supremacists typically believe Muggle-borns to be magically deficient, despite examples to the contrary, such as Hermione Grangerand Lily Evans, who are exceptionally skilled in their abilities.
Pure-blood supremacists refer to Muggle-borns with the offensive derogatory term Mudblood. Hagrid was shocked to find out that Draco Malfoy uttered the term to Hermione in order to insult and provoke her, since the slur is never used in proper conversations. Hermione decided to reclaim and use the term "Mudblood" with pride instead of shame in an effort to defuse its value as a slur.
During Voldemort's rule, Muggle-borns were legally required to register with the Muggle-Born Registration Commission. During this time, the Department of Mysteries "discovered" that Muggle-borns acquired their magic by "stealing" magic and wands from real wizards. Other wizards and witches rejected this notion, such as Ron Weasley, who asks how it is even possible to steal magic. After the fall of the regime, Dolores Umbridge (head of the Commission) and the supporters of this ideology are imprisoned for crimes against Muggle-borns.