A flying buttress is a specific form of buttressing most strongly associated with Gothic church architecture. The purpose of any buttress is to resist the lateral forces pushing a wall outwards (which may arise from stone vaulted ceilings or from wind-loading on roofs) by redirecting them to the ground. The characteristic of a flying buttress is that the buttress is not in contact with the wall all the way to the ground; so that the lateral forces are transmitted across an intervening space. Flying buttress systems have two key components - a massive vertical masonry block (the buttress) on the outside of the building and a segmental or quadrant arch bridging the gap between that buttress and the wall (the 'flyer').