AP World History 101. Feudalism and the Crusades Video. Feudalism developed in Western Europe at around 800 C.E. from the remnants of the Western Roman Empire. As a result of central authority being unable to perform its functions and prevent the rise of local powers, this decentralized organization formed.
LEED, which stands for Leadership in Energy and Environmental Design, is a certification program focused primarily on new, commercial-building projects and based upon a points system. The more points you earn, the higher your rating.
An example of LEED is the process used to look at the surface structure of crystals. The surface is bombarded with low energy electrons and, when they are diffracted off the surface, that motion can be observed on a phosphorescent screen.