I have NO experience on network programming at all. Recently I learnt something, they are interesting. I am trying to summarize what I have learned as my own understanding way -- the mail system. Special thanks to Barteur Zhou.
我以前从没有过网络编程的经验和知识。最近学了一些，还挺好玩的。在这里，我想试试用自己的理解方式来总结下我近来所学的知识 -- 用写信的方式来类比。特别感谢 Barteur Zhou。