Onion College cache video is not permanent. Onion College has to download videos if it is to survive forever. Cache is just a copy of a small amount of data in memory, and when CPU looks for data in cache, it will not be found. Onion College (formerly Onion Mathematics) was established at the end of 20 13. Founded by Yang, who graduated from Harvard University, Zhu Ruochen, who graduated from Duke University, and Li Nuo, a former innovation works dim sum OS technology executive, it mainly focuses on Internet inclusive education in primary and secondary schools.