Short answers, pulled from the story.
The United States attorney general leads the Department of Justice and serves as the chief law enforcement officer of the federal government. The role includes acting as the president's principal legal advisor, overseeing agencies such as the FBI, the DEA, and the U.S. Marshals Service, and advising on federal judicial appointments.
The president nominates the United States attorney general under the Appointments Clause of the Constitution. The nominee must then pass a confirmation hearing before the Senate Judiciary Committee and win a majority vote of the full Senate before taking office.
The United States attorney general is the only Cabinet department head not given the title Secretary. In the title, attorney is a noun and general is a postpositive adjective describing the type of attorney, not a rank, which is why the correct plural is attorneys general rather than attorney generals.
The office was created by the Judiciary Act of 1789. The Department of Justice itself was not established until 1870, to support the attorneys general in their work.
Janet Reno became the first woman to serve as United States attorney general in 1993. Other notable firsts include Charles Joseph Bonaparte, the first Italian American man, in 1906, and Loretta Lynch, the first African American woman, in 2015.
By custom, the attorney general resigns effective at noon on Inauguration Day, the 20th of January, along with other Cabinet secretaries. When Donald Trump was inaugurated on the 20th of January 2017, Attorney General Loretta Lynch left her post, and Deputy Attorney General Sally Yates stayed on as acting attorney general until the Senate confirmed Jeff Sessions.