This chapter mainly introduces the mechanism and procedures of OTA. Firstly, it describes the basic procedures and ways of performing OTA. Then it presents the functions of the partition table and the fields related to OTA. In actual mass production, it is also necessary to enable the rollback and anti-rollback functions accordingly to further improve the stability and reliability of the device. Finally, according to the practical example provided, you can either complete the firmware update through the local host or push the update message to the device from the cloud through ESP RainMaker.