2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/109001This is a survey paper on several aspects of differential geometry for the last 30 years, especially in those areas related to non-linear analysis. It grew from a talk I gave on the occasion of seventieth anniversary of Chinese Mathematical Society. I dedicate the lecture to the memory of my teacher S.S. Chern who had passed away in December 2004.To appear in Survey in Differential Geometry, Vol. XDifferential Geometrytext