A more thorough explanation:

Definition: Chief Justice is the highest-ranking judge in a supreme court. This title can be used for state or federal chief justices, but it is mostly used for the Chief Justice of the U.S. Supreme Court. The Chief Justice is the most senior member of the court and has unique duties in addition to those of the associate justices. For example, the Chief Justice presides over presidential impeachment trials in the federal judiciary.

For instance, the current Chief Justice of the U.S. Supreme Court is John Roberts. He is responsible for leading the court and making sure that it functions properly. He also has the power to influence the historical record by writing the majority opinions when in the majority.

At the state level, the office of the Chief Justice may be provided for in the state's constitution or other legislation. For example, the California Constitution explicitly states that the Supreme Court consists of the Chief Justice of California and six associate justices.

In summary, the Chief Justice is the highest-ranking judge in a supreme court, responsible for leading the court and performing unique duties. The Chief Justice has the power to influence the historical record and is selected through the same process as associate justices.