Importance of a keystone in an arch?

clue.less

this site: http://www.cpo.com/weblabs/chap3/archf.htm

helped me to understand the forces acting on each side block an arch, but it doesn't give any information about the keystone.

Can someone explain a keystone's importance? What is its function, and how does it keep itself from falling?

clue.less	Importance of a keystone in an arch? Tweet this site: http://www.cpo.com/weblabs/chap3/archf.htm helped me to understand the forces acting on each side block an arch, but it doesn't give any information about the keystone. Can someone explain a keystone's importance? What is its function, and how does it keep itself from falling?