The Constitution of India provides special Emergency Provisions in Part 18 under Articles 352 to 360. These are the provisions provided by the Constitution makers to safeguard the sovereignty, unity, security of the country and its democratic as well as political situations during the time of crisis. Emergency means a combination of unforeseen situations that can cause a great threat to lives, health, economy, peace by creating catastrophic situations.
When the Emergency is imposed in India, the federal system of the country converts into a unitary one and the whole power goes in the hands of the central government. Once Dr B R Ambedkar expressed his views on this special feature of Constitution in constituent assembly by saying:

"All Federal systems including American are placed in a tight mould of federalism. No matter what the circumstances, it cannot change its form and shape. It can never be unitary. On the other hand, the constitution of India can be both unitary as well as Federal according to the requirement of the time and circumstances. In normal times it is free to work as a federal system but in times of emergency it is designed to make it work as though it was a unitary system."
There is a provision of three types of emergency in India: National Emergency, President's Rule and Financial Emergency.
Article 352 of the Indian constitution provides for a National Emergency. It is imposed by the President at a time of war, external aggression or arms rebellion to ensure the security of the nation. It is denoted as 'proclamation of emergency' by the constitution.
When the emergency situation is declared on the ground of war or external aggression this kind of emergency is known as 'External Emergency' and when it is declared in the situation of arms rebellion it is known as 'Internal emergency'. Here are some points that come handley from an exam perspective:
This is the second type of emergency provided in the article 356. In the case of failure of state governance, the centre has a right to take over all the executive powers of the particular state. It is also known as 'State Emergency' or 'Constitutional Emergency'. President's rule can be imposed on 2 grounds as per article 356 and 365. Article 365 says when the situation becomes out of the hands of the state government, the President can take the direct charge of the state. Here are some points to be noted for President's rule:
Under Article 360, provision of financial emergency is given. At the time of economic crisis or a situation which can cause financial instability, the President has a right to impose financial emergency under Article 360 of Indian Constitution. Important points to be noted here for financial emergency:
Article 352: Proclamation of emergency.
Article 353: Effects of proclamation of Emergency.
Article 354: Application of provisions relating to distribution of revenues while a proclamation of emergency is in operation.
Article 355: Duty of the union to protect the states against external aggression and internal disturbance.
Article 356: Provisions in case of failure of constitutional machinery in States.
Article 357: Exercise of Legislative powers under proclamation issued under article 356.
Article 358: Suspension of provisions of article 19 during emergencies.
Article 359: Suspension of the enforcement of the rights conferred by part 3 during emergency.
Article 360: Provisions as to financial emergency.