TCP，UDP，HTTP

使用图表非常系统介绍了TCP和UDP的区别

https://blog.fundebug.com/2019/03/22/differences-of-tcp-and-udp/

举了一个TCP/IP通讯的例子，发送/接收邮件

https://blog.csdn.net/freekiteyu/article/details/72236734

介绍了socket和TCP/IP的关系

https://cloud.tencent.com/developer/article/1347105

ROS使用TCP/IP进行通讯

http://wiki.ros.org/ROS/TCPROS