Windows下暴露的对开发人员的接口叫做应用程序编程接口，就是我们常说的API。我们在写应用层应用程序软件的时候都是通过调用各种API来实现 的。有些时候，我们需要监控其他程序调用的API，也就是，当其他应用程序调用我们感兴趣的API的时候，我们在他调用前有一个机会做自己的处理，这就是 HOOK API的涵义。

-Windows exposed to developers interface called the application programming interface, is what we often say API. We are all realized by calling various API when writing application layer application software. Sometimes, we need to monitor call other procedures of API, that is, when other applications we are interested in API, we have a chance at him before the call to do their own processing, this is the meaning of HOOK API.