The chief justice heads the judicial branch of the United States federal government. The individual in this position presides over the other eight members of the supreme court who are referred to as associate justices. All nine justices are nominated by the U.S. President and each must be confirmed by a majority vote of the U.S. senate after which they have lifetime appointments.
Being chief justice is highly prestigious because the individual in this position issues rulings over controversial cases that could shape the judicial history of the country. However while the chief justice is honored by being first to enter the courtroom and first to cast a vote when the justices deliberate the vote of the chief justice carries the same legal weight as the votes of the other eight justices. However the chief justice decides who author of the Opinion of the Court which has an indirect influence on the "flavor" of the opinion.
Although this is a rare occurrence the chief justice presides when there is a presidential impeachment hearing. Also the chief justice writes an annual report to congress about the state of the federal court system. A traditional though not mandatory duty of this office is swearing in the U.S. president at inaugurations. The chief justice serves an annual term from October to the end of June with two weeks of hearing cases alternating with two weeks of writing opinions.
According to Ehow.com in order to become a chief justice a person has to be a member of a state bar often starting out as a prosecuting attorney and then serving in judgeships in local appellate and federal courts. A chief justice earns an annual salary of approximately $224000.