The Inquisitions were courts established by leaders in the Roman Catholic Church to combat alleged heresy (wrong doctrinal teaching). There were various Inquisition movements (Spanish, Medieval, Portuguese, Roman, etc). Tragically, thousands (some 3,000-5,000 in Spain alone) were put to death from these trials.
These inquisitions were an abuse of power by leaders in the Roman Catholic Church and completely inconsistent with Jesus’ teaching.