G-Webs as certain trivalent graphs on the surfaces, appear naturally in the G-skein algebra and its classical limit the regular function ring of the G character variety. I will explain how we introduce their intersection number to parameterize a basis of the algebra for SL3 (joint work with Daniel Douglas, Linhui Shen, Daping Weng) and Sp4 (joint work with Tsukasa Ishibashi, Wataru Yuasa).