The Ministry employs aurors to pursue and apprehend Dark wizards. According to Minerva McGonagall, the Auror Office takes in new recruits with a minimum of 5 N.E.W.T.s (with marks no lower than "Exceeds Expectations"). She suggests that Potions, Defence Against the Dark Arts, Transfiguration, Charms, and Herbology N.E.W.T.s are the most appropriate subjects for someone who aspires to gain admission to the training program. A potential recruit also has to pass "a series of character and aptitude tests." Nymphadora Tonks mentions that the program's courses of study include "Concealment and Disguise" and "Stealth and Tracking," and that the training is hard to pass with high marks.