Adding higher obstructions (P fields) into moduli spaces of maps, one represent Gromov Witten invariants of quintic hypersurfaces as Landau Ginzburg type invariants. By promoting Kahler parameter into fields on worldsheet, one obtains a moduli space connecting Gromov Witten invariants with Fan-Jarvis-Ruan-Witten invariants. This moduli is called Mixed Spin P (MSP) fields. We then can approach structures of all genus quintic GW invariants, such as holomorphic ambiguity, CY-LG correspondence, and algorithms.