Yii Framework

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What is Yii ​

Yii is a high-performance, package-based PHP framework for developing modern applications. The name Yii (pronounced Yee or [ji:]) means "simple and evolutionary" in Chinese. You can also think about it as an acronym for Yes It Is!

What's Yii Best for ​

Yii is a generic Web programming framework. You can use it for developing all kinds of Web applications using PHP. Because of its architecture and sophisticated caching support, it's especially suitable for developing large-scale applications such as portals, content management systems, e-commerce, REST APIs, etc.

How does Yii Compare with Other Frameworks ​

If you're already familiar with another framework, you may appreciate knowing how Yii compares:

  • Yii takes the philosophy of being practical and helpful achieving:

    • Performance in both development and execution.
    • Convenient customizable defaults.
    • Practice-orientation.
    • Simplicity.
    • Explicitness.
    • Consistency.

    Yii will never try to over-design things mainly for the purpose of following some design patterns.

  • Yii extensively uses PSR interfaces with the ability to reuse what PHP community created and even replace core implementations if needed.

  • Yii is both a set of libraries and a full-stack framework providing many proven and ready-to-use features: caching, logging, template engine, data abstraction, development tools, code generation; and more.

  • Yii is extensible. You can customize or replace every piece of the core's code. You can also take advantage of Yii's solid architecture to use or develop redistributable packages.

  • High performance is always a primary goal of Yii.

Yii is backed up by a strong core developer team financially backed from an OpenCollective foundation, as well as a large community of professionals constantly contributing to Yii's development. The Yii developer team keeps a close eye on the latest Web development trends 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 via simple and elegant interfaces.

Yii versions ​

Yii currently has three major versions available: 1.1, 2.0 and 3.0.

  • Version 1.1 is the old generation and is now in the feature freeze bugfix mode.
  • Version 2.0 is a current stable version that's in the feature freeze bugfix mode.
  • Version 3.0 is the current version in development. This guide is mainly about version 3.

Requirements and prerequisites ​

Yii3 requires PHP 8.0 or above, but some packages also support PHP 7.4.

Using Yii requires basic knowledge of object-oriented programming (OOP), as Yii is a pure OOP-based framework. Yii3 also makes use of the latest features of PHP, such as type declarations and generators. Understanding these concepts will help you pick up Yii3 faster.