The introductory statement of the Constitution that declares its source of authority, the nature of the Indian State, the objectives it seeks to secure, and the date of its adoption.
The keyword order, the 42nd Amendment additions, and the dates are high-frequency static-fact items, often as fill-in or matching questions.
The Preamble is amendable but not a source of justiciable power by itself; 26 November 1949 (adoption) versus 26 January 1950 (commencement); the "Socialist Secular" wording was added in 1976, not in the original 1949 text.
"We, the People" declare a Sovereign Socialist Secular Democratic Republic securing Justice, Liberty, Equality, Fraternity (adopted 26 November 1949).