According to the Constitution, there shall be a Council of Ministers with the Prime Minister at the head to aid and advise the President who shall act according to that advice. The President is bound to exercise all the powers exactly according to the advice of the Council of Ministers, which is headed by the Prime Minister. It is the Prime Minister who is the real head of the Union executive.
The Prime Minster is appointed by the President, but the President has to invite only that person to be the Prime Minister, who is the leader of the majority in the Lok Sabha.
To be the Prime Minister, the person has to be a Member of Parliament. If he or she is not a Member at the time of appointment, he or she has to acquire it within six months from the state of his appointment as PM.
Prime Minister makes and unmakes the Council of Ministers. It is on his or her recommendations that the President appoints the members of the Council of Ministers and distributes portfolios among them.
The Prime Minister presides over the meetings of the Cabinet and communicates its decisions to the President. The Prime Minister acts as the link between the President and the Council of Ministers.
The Prime Minister is the Ex-officio Chairman of the Planning Commission as well as of the National Development Council.
The Prime Minister represents the nation at the international conferences as the head of the government.