API 是应用程序编程接口.这实际上是许多不同类型事物的通用术语.我假设您指的是通常基于 RESTful 或基于 SOAP 的Web API".使用的 API 类型确实因服务而异.有些有多种使用 API 的方式，例如 Amazon 有基于 REST 和基于 SOAP 的服务.

An API is an Application Programming Interface. This is really a generic term for a lot of different sort of things. I'm assuming you mean "Web APIs" which are usually RESTful or SOAP based. The sort of API that is used really differs from one service to another. Some have multiple ways of working with the API, like Amazon has REST based and SOAP based services.

如果您是从客户端开始，***的入门方法是真正开始学习 Javascript，然后学习 JQuery.然后从那里选择您想要编程的服务.您可以通过编写 Google Maps API 来学习很多 Javascript.这可能是***的起点，因为它是一个非常简洁的系统，不会太难，需要您具备良好的 Javascript 知识水平(您可以在此过程中学习).

The best way to get started if you are doing this from the client side, is to really start learning Javascript and then learn JQuery. Then from there choose a service you'd like to program to. You could learn a lot of Javascript by coding for the Google Maps API. This is probably the best place to start as it is a pretty neat system, not too difficult, requires you to have a good level of knowledge of Javascript (which you can learn along the way).