A more thorough explanation:

A United States Magistrate Judge is a type of federal judicial officer who handles pretrial matters in both civil and criminal cases. They may also conduct civil trials or criminal misdemeanor trials. This position was previously known as a United States Magistrate before 1990.

For example, a United States Magistrate Judge may be responsible for overseeing the discovery process in a civil case, which involves gathering evidence from both parties. They may also preside over a criminal misdemeanor trial, such as a case involving a minor offense like disorderly conduct.

Overall, a United States Magistrate Judge plays an important role in the federal court system by assisting district judges with various aspects of their cases and helping to ensure that the legal process runs smoothly.