Article 368: "Parliament may in the exercise of its constituent power amend by way of addition, variation or repeal any provision of this Constitution in accordance with the procedure laid down in this article."
There are three ways in which the Constitution can be amended:-
Amendment by a simple majority of the Parliament
Amendment by a special majority of the Parliament
Amendment by a special majority of the Parliament and the ratification of at least half of the state legislatures.
Amendment by a simple majority-
Admission or establishment of new states, Formation of new states, Rules of procedure in Parliament, Salaries and Allowances, etc are covered under this.
Amendment by the special majority-
The special majority- a majority of 2/3rd members present and voting supported by more than 50% of the total strength of the house.
The provisions which can be amended by this way include (i) Fundamental Rights; (ii) Directive Principles of State Policy; and (iii) All other provisions which are not covered by the first and third categories.
Amendment by a special majority of the Parliament and the ratification of at least half of the state legislatures-
Those provisions of the Constitution which are related to the federal structure of the polity can be amended by this.
For instance, the election of the president, distribution of legislative powers between union and states, any of the lists in the seventh schedule, etc.