This is a rough translation from one article on my old Chinese blog. The original one was written on Sept. 19th, 2017. Last weekend, when I was playing a CTF game, I got an interesting challenge about GraphQL. That was my first time to see GraphQL. At that time, I spent some time on Google, trying to get more detail about it, but finally found a few things impressive. This time, I took a twice look at it. Although it may lack some depth, it is enough to be a note.