Magistrates are judicial officers who preside over criminal and civil matters in Magistrates' Courts. They can remand defendants in custody, issue arrest warrants, and handle civil claims under £25,000. Magistrates must be over 18, have no criminal convictions, and possess sound judgment, communication skills, and the ability to make fair and impartial decisions. Magistrates are appointed by the Lord Chancellor and serve terms of 5 years, which can be renewed.