According to Indian Culture website:
The Preamble to the Constitution of India serves as an introductory statement that outlines the fundamental values and guiding principles of the nation. It declares India to be a Sovereign, Socialist, Secular, Democratic Republic committed to Justice, Equality, and Liberty for its people. Although the Preamble does not grant substantive rights and is not enforceable in courts, it has been regarded by various Indian courts as a guiding light, reflecting the core constitutional values embodied in the Constitution.

WE, THE PEOPLE OF INDIA,
having solemnly resolved to constitute India into a SOVEREIGN, SOCIALIST, SECULAR, DEMOCRATIC REPUBLIC and to secure to all its citizens:
JUSTICE, social, economic, and political;
LIBERTY of thought, expression, belief, faith, and worship;
EQUALITY of status and of opportunity;
and to promote among them all
FRATERNITY assuring the dignity of the individual and the unity and integrity of the Nation;
IN OUR CONSTITUENT ASSEMBLY this twenty-sixth day of November, 1949, do HEREBY ADOPT, ENACT AND GIVE TO OURSELVES THIS CONSTITUTION.
This Preamble encapsulates the essence of the Constitution and the aspirations of its framers for the nation.
The Preamble to the Constitution of India has been amended only once, through the 42nd Amendment Act, 1976. This amendment was made during the Emergency period under the leadership of Prime Minister Indira Gandhi.
Changes Made by the 42nd Amendment:
- Added “Socialist”:
- Highlighted the commitment to a society based on equality, with no concentration of wealth or resources in a few hands.
- Added “Secular”:
- Emphasized the state’s neutrality toward all religions and its commitment to ensuring religious freedom.
- Added “Integrity”:
- Reinforced the idea of maintaining the unity and integrity of the nation.
Original Preamble (1949):
“WE, THE PEOPLE OF INDIA, having solemnly resolved to constitute India into a SOVEREIGN DEMOCRATIC REPUBLIC and to secure to all its citizens: JUSTICE, LIBERTY, EQUALITY, and FRATERNITY assuring the dignity of the individual and the unity of the Nation.”
Amended Preamble (Post-42nd Amendment):
“WE, THE PEOPLE OF INDIA, having solemnly resolved to constitute India into a SOVEREIGN SOCIALIST SECULAR DEMOCRATIC REPUBLIC and to secure to all its citizens: JUSTICE, LIBERTY, EQUALITY, and FRATERNITY assuring the dignity of the individual and the unity and integrity of the Nation.”
This amendment expanded the scope of the Preamble to reflect the socio-economic and political aspirations envisioned during the mid-1970s. Despite being a guiding principle rather than an enforceable part of the Constitution, the Preamble holds significant importance in understanding the spirit of the Indian Constitution.