Final answer:
In Gothic churches, the flying buttress was used to support exterior walls and allow for larger stained glass windows by transferring weight and lateral thrust away from the walls.
Step-by-step explanation:
In a Gothic church, the structural element traditionally built against an exterior wall to provide support and brace it against strong winds is known as a flying buttress. Initially, these were not included in the original architectural designs, but as the construction of Gothic churches progressed, the thinner walls began to fracture under stress. Architects then incorporated flying buttresses at critical points of structural weakness. These supports effectively stop the fracturing by transferring the forces of gravity and lateral thrust away from the walls and into the ground. Beyond their structural purpose, flying buttresses allowed for larger stained glass windows and increased interior illumination, as they enabled walls to be thinner and have spaces for more windows. These architectural features are iconic to Gothic architecture and are closely associated with the expression of the divine through the play of light inside these sacred spaces.