The Spanish Inquisition was an ecclesiastical tribunal established in 1478 by the Catholic Monarchs, Ferdinand and Isabella of Spain.

Unlike the earlier medieval inquisition, it was under the direct control of the Spanish monarchy.

Its primary original purpose was to enforce religious orthodoxy and combat heresy, particularly among 'conversos' (Jews who had converted to Christianity).

There was a widespread and often paranoid belief that many conversos were secretly practicing Judaism.

The Inquisition's methods were infamous, involving secret testimonies, the use of torture to extract confessions, and a lack of legal rights for the accused.

The public sentencing of heretics was known as an 'auto-da-fé' ('act of faith'), which could include punishments ranging from public penance to being burned at the stake.

The first Grand Inquisitor, Tomás de Torquemada, became a symbol of its cruelty and fanaticism.

Later, the Inquisition's focus expanded to include Protestants, humanists, and others accused of heresy.

It created a powerful climate of religious intolerance and intellectual censorship in Spain.

The Spanish Inquisition was not formally abolished until the 19th century.