This chapter provides you with a brief overview of several of the essential APIs and frameworks provided by Liferay to developers. An API is any programing interface that you can invoke from your own code either directly through a Java invocation or through web services to perform a certain action. A framework, in this context, is a set of APIs and configuration that is designed for an specific purpose such as enhancing your applications with a permission system, with tags, with categories, comments, etc.
This chapter will keep evolving with more information about the existing APIs and frameworks and how to use it. So look back for more information often.