docs: guide/README.md

Author: geekdada

docs/guide/README.md

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 title: Guide
-navTitle: Egg Guide
+navTitle: Guide
 toc: false
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-guide
+In this guide, we'd thoroughly introduce you every bit of Egg. You can also find guides about the applicable situations of Egg, components how-to, common functions and properties, extendability and testing.
+
+## MVC
+
+Egg is a web application framework written in Node.js. It is designed based on the MVC principle, which is commonly seen among other web application frameworks written in Node.js, like Express.js.
+
+Before we step into the details, we strongly recommend you to learn [the structure of an Egg application].
+
+There're some basic concepts that you need to know:
+
+- [Middleware]: Same as `Koa`'s middleware and similar to `Filter` in Java's world.
+- [Controller]: Response to the incoming requests and performs interactions on the data models or calling the services.
+- [Router]: Dispatches incoming requests to designated controllers.
+- [Service]: A bunch of magic functions that contain your business logics.
+- [Application]: A handy object includes the [configurations] of the application. It can be accessed globally.
+- [Context]: Every user request has a context. It describes the request and defines the response.
+- Besides, there're [Cookie], [Session], [Helper], etc.
+
+## Features
+
+Egg provides a range of utilities you can use in your day to day development.
+
+- [Plugins]: The foundation of Egg's eco-system. You can extend your applications using plugins just in one minute.
+- [Lifecycle]: Allow you to run your own code at different stages.
+- [Logs]: Logging anything to anywhere. It is crucial for monitoring and debugging.
+- [Error handling]: Make the application robust.
+- [Security]: Be safe.
+- Last but not least, [file uploading], [i18n].
+
+[the structure of an Egg application]: ./directory.md
+[Controller]: ./controller.md
+[Service]: ./service.md
+[Router]: ./router.md
+[Cookie]: ./cookie.md
+[Session]: ./session.md
+[Application]: ./application.md
+[Context]: ./context.md
+[Middleware]: ./middleware.md
+[Plugins]: ./plugin.md
+[Lifecycle]: ./lifecycle.md
+[configurations]: ./config.md
+[Logs]: ./logger.md
+[Error handling]: ./error_handler.md
+[Helper]: ./helper.md
+[Security]: ../ecosystem/security/
+[file uploading]: ./upload.md
+[i18n]: ./i18n.md