Yii is a generic Web programming framework, meaning that it can be used for developing all kinds
of Web applications based on PHP. Because of its component-based architecture and sophisticated caching
support, it is especially suitable for developing large-scale applications such as portals, forums, content
management systems (CMS), e-commerce projects, RESTful Web services, and so on.
Yii 是一个通用的 Web 编程框架，意味着它可以用于开发任意类型的 PHP Web 应用程序。由于它基于组件的架构和精致的缓存支持，它
特别适用于开发大型的应用程序，例门户，论坛，内容管理系统（CMS），电子商务项目，RESTful Web 服务等等。
How does Yii Compare with Other Frameworks?
Yii 和其他框架作个比较呢？
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- Like most PHP frameworks, Yii implements the MVC (Model-View-Controller) design pattern and promotes code
organization based on this pattern.
- Yii takes the philosophy that code should be written in a simple yet elegant way. It will never try to
over-design things mainly for the purpose of following some design pattern.
- Yii is a full-stack framework providing many proven and ready-to-use features, such as: query builders
and ActiveRecord, for both relational and NoSQL databases; RESTful API development support; multi-tier
caching support; and more.
- Yii is extremely extensible. You can customize or replace nearly every piece of core code. You can also
take advantage of its solid extension architecture, to use or develop redistributable extensions.
- High performance is always a primary goal of Yii.
Yii is not a one-man show, it is backed up by a [strong core developer team][] as well as a large community
with many professionals constantly contributing to the development of Yii. The Yii developer team
keeps a close eye on the latest trends of Web development, and on the best practices and features
found in other frameworks and projects. The most relevant best practices and features found elsewhere are regularly incorporated into the core framework and exposed
Yii 开发者团队始终对 Web 开发最新潮流和其他框架及项目中的优秀实践和特性保持密切的关注，其他地方出现的最相关优秀实践及
特性会被不定期的整合进核心框架中，并提供简单优雅的接口。
[强大的开发者团队]:http://www.yiiframework.com/about/
Yii 版本
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Yii currently has two major versions available: 1.1 and 2.0. Version 1.1 is the old generation and is now in maintenance mode. Version 2.0 is a complete rewrite of Yii, adopting the latest
technologies and protocols, including Composer, PSR, namespaces, traits, and so forth. Version 2.0 represents the latest
generation of the framework and will receive our main development efforts in the next few years.
Using Yii requires basic knowledge about object-oriented programming (OOP), as Yii is a pure OOP-based framework.
Yii 2.0 also makes use of the latest features of PHP, such as [namespaces](http://www.php.net/manual/en/language.namespaces.php) and [traits](http://www.php.net/manual/en/language.oop5.traits.php). Understanding these concepts will help
