Grid Technologies proposed by Globus project has been used to establish,manage,and exploit cross-organi-zational vitual organizations sharing relationships. Grid technologies are structured by the Grid architecture. The Gridarchitecture is an extensible and open architectural structure which identifies fundamental system components,speci-fies the purpose and fuctions of these components,and indicates how these components interact with one another. Inthis paper ,The Globus project and leaders of itare introduced brifly,then description of various layers of the Grid ar-chitecture including their purposes and functions are presented in detail, and Grid protocols & sevices(and APIs) de-fined in Globus Toolkits and Grid architecture in practice are also disscussed.