Under Article II, Section 2 of the U.S. Constitution, the President "shall nominate, and by and with the advice and consent of the Senate, shall appoint ambassadors, other public ministers and consuls, judges of the Supreme Court, and all other officers of the United States, whose appointments are not herein otherwise provided for..."
The Senate provides advice and consent for all judicial nominations for federal courts created under Article III of the U.S. Constitution. It also provides advice and consent for cabinet level posts and executive level agency positions. Such nominations are referred to the appropriate Senate Committee, which often holds a hearing where the nominee provides testimony and responds to questions. Then the Committee refers the nomination to the full Senate for a vote.
The resources on this page provide information about the Senate's role and procedures during the nomination process.