The Oath Of Office

"I do solemnly swear (or affirm) that I will support and defend the Constitution of the United States against all enemies foreign and domestic; that I will bear true faith and allegiance to the same; that I take this obligation freely without any mental reservation or purpose of evasion; and I will well and faithfully discharge the duties of the office on which I am about to enter,
so help me God." 

The Office Of The Vice President

The office of the vice president was created at the constitutional convention in 1787.  The vice president has two official duties
according to the Constitution:

1.  To preside over the Senate, however the vice president is not allowed to engage
in the debate, nor vote unless there is a tie.

2.  To assume the presidency in the event
of the death, resignation, removal or incapacitation of the president.

All other duties assigned are by statute
or by the request of the president.

The Vice Presidency - A Brief Overview

Initially, the person who received the second highest electoral vote for president became vice president.  The flaw in this system became evident in 1800 when Thomas Jefferson and Aaron Burr each received 73 electoral votes.  Congress adopted the 12th Amendment to the Constitution in 1804 which provided for separate ballots for the two offices and defined under what circumstances the vice president would become president.    Fourteen times in history has the vice president become president.  Eight upon the previous president's death.  Five were elected in their own right and one took over upon the resignation of the president.