Gene therapy is a medical technique that involves introducing, removing, or altering genetic material within a person's cells to treat or prevent disease. This approach aims to correct defective genes responsible for disease development or to provide new functions to cells. Methods include replacing mutated genes, inactivating malfunctioning genes, or introducing new genes to help fight a disease. Gene therapy holds promise for treating a range of conditions, including genetic disorders, some types of cancer, and certain viral infections. However, it is still largely experimental, with ongoing research to ensure its safety and effectiveness.