(CNN)Here's a look at what you need to know about Supreme Court nominations.
Under Article II of the Constitution, the President nominates justices to the Supreme Court, with the "advice and consent of the Senate."
If a vacancy occurs when Congress is not in session, a recess appointment allows an appointee to serve without Senate approval until Congress reconvenes.
One hundred and sixty nominations have been submitted to the Senate. There have been 124 confirmations, and 112 individuals have served on the Supreme Court.
The American Bar Association's Standing Committee on the Federal Judiciary evaluates all nominees to the Supreme Court for the Justice Department and the Senate Judiciary Committee. The organization has three possible rankings: qualified, well-qualified, and not qualified.
Nine men have been appointed chief justice of the United States without having previously served as an associate justice: William Howard Taft, Earl Warren, Melville W. Fuller, Warren E. Burger, Fred M. Vinson, Morrison R. Waite, Salmon P. Chase, Roger B. Taney (nominated as associate justice but never confirmed, so re-nominated as chief justice), John Marshall, Oliver Ellsworth, John Jay, and John Roberts.
Three justices served on the Supreme Court before being appointed chief justice: William Rehnquist, Charles Evans Hughes, and John Rutledge, who served as interim chief justice for less than six months.
Franklin D. Roosevelt appointment nine justices during his 12-year presidency, the most since George Washington. Jimmy Carter is the only U.S. president to complete a full term of office and never have the opportunity to nominate a justice.
1952 - Presidents begin consulting the American Bar Association before making Supreme Court nominations.
1950s - President Dwight Eisenhower makes recess appointments of Earl Warren, Potter Stewart and William J. Brennan. All three are later confirmed by the Senate.
1955 - Nominees begin appearing before the Senate Judiciary Committee for confirmation hearings.
1981 - Senate Judiciary Committee Hearings are televised for the first time.
1987 - Robert Bork is the last Supreme Court nominee to be rejected by the Senate. The next nominee, Douglas Ginsburg, withdraws over allegations of drug use. Anthony Kennedy takes the seat.
March 22, 2001 - The Bush Administration announces it will not consult with the ABA before judicial candidates are formally nominated. The administration says it is concerned about the ABA's semi-official role in the process.
January 31, 2006 - Samuel Alito is confirmed by the Senate (58-42) as an associate justice, replacing Sandra Day O'Connor. He is immediately sworn in by Chief Justice John Roberts.
August 8, 2009 - Sonia Sotomayor is sworn in as the 111th Supreme Court Justice.
May 10, 2010 - President Barack Obama nominates Solicitor General Elena Kagan to fill the seat of retiring Justice John Paul Stevens.
August 7, 2010 - Kagan is sworn in as the 112th Supreme Court Justice.