What is OpenID?OpenID 是什么？

OpenID is an open, decentralized, free framework for user-centric digital identity.
OpenID starts with the concept that anyone can identify themselves on the Internet the same way websites do-with a URI (also called a URL or web address). Since URIs are at the very core of Web architecture, they provide a solid foundation for user-centric identity.
The first piece of the OpenID framework is authentication -- how you prove ownership of a URI. Today, websites require usernames and passwords to login, which means that many people use the same password everywhere. With OpenID Authentication , your username is your URI, and your password (or other credentials) stays safely stored on your OpenID Provider (which you can run yourself, or use a third-party identity provider).
To login to an OpenID-enabled website (even one you've never been to before), just type your OpenID URI. The website will then redirect you to your OpenID Provider to login using whatever credentials it requires. Once authenticated, your OpenID provider will send you back to the website with the necessary credentials to log you in. By using Strong Authentication where needed, the OpenID Framework can be used for all types of transactions, both extending the use of pure single-sign-on as well as the sensitivity of data shared.
Beyond Authentication, the OpenID framework provides the means for users to share other components of their digital identity. By utilizing the emerging OpenID Attribute Exchange specification, users are able to clearly control what pieces of information can be shared by their Identity Provider, such as their name, address, or phone number.

OpenID 是一个以用户为中心的数字身份识别框架，它具有开放、分散、自由等特性。
OpenID 的创建基于这样一个概念：我们可以通过 URI （又叫 URL 或网站地址）来认证一个网站的唯一身份，同理，我们也可以通过这种方式来作为用户的身份认证。由于URI 是整个网络世界的核心，它为基于URI的用户身份认证提供了广泛的、坚实的基础。
OpenID 系统的第一部分是身份验证，即如何通过 URI 来认证用户身份。目前的网站都是依靠用户名和密码来登录认证，这就意味着大家在每个网站都需要注册用户名和密码，即便你使用的是同样的密码。如果使用 OpenID ，你的网站地址（URI）就是你的用户名，而你的密码安全的存储在一个 OpenID 服务网站上（你可以自己建立一个 OpenID 服务网站，也可以选择一个可信任的 OpenID 服务网站来完成注册）。
登录一个支持 OpenID 的网站非常简单（即便你是第一次访问这个网站也是一样）。只需要输入你注册好的 OpenID 用户名，然后你登录的网站会跳转到你的 OpenID 服务网站，在你的 OpenID 服务网站输入密码（或者其它需要填写的信息）验证通过后，你会回到登录的网站并且已经成功登录。 OpenID 系统可以应用于所有需要身份验证的地方，既可以应用于单点登录系统，也可以用于共享敏感数据时的身份认证。
除了一处注册，到处通行以外，OpenID 给所有支持 OpenID 的网站带来了价值－－共享用户资源。用户可以清楚的控制哪些信息可以被共享，例如姓名、地址、电话号码等。