We recognize that you need stability from the Angular framework. Stability ensures that reusable components and libraries, tutorials, tools, and learned practices don't become obsolete unexpectedly. Stability is essential for the ecosystem around Angular to thrive.
We also share with you the desire for Angular to keep evolving. We strive to ensure that the foundation on top of which you are building is continuously improving and enabling you to stay up-to-date with the rest of the web ecosystem and your user needs.
我们也和你一样希望 Angular 能持续演进。我们会努力确保这些你用于构建应用的基础能得到持续的改进，并让你能及时同步到 Web 生态系统的其它部分的最新进展，用户需求也是一样。
This document contains the practices that we follow to provide you with a leading-edge app development platform, balanced with stability. We strive to ensure that future changes are always introduced in a predictable way. We want everyone who depends on Angular to know when and how new features are added, and to be well-prepared when obsolete ones are removed.
The practices described in this document apply to Angular 2.0 and later. If you are currently using AngularJS, see [Upgrading from AngularJS](guide/upgrade "Upgrading from Angular JS"). _AngularJS_ is the name for all v1.x versions of Angular.
Angular version numbers indicate the level of changes that are introduced by the release. This use of [semantic versioning](https://semver.org/ "Semantic Versioning Specification") helps you understand the potential impact of updating to a new version.
Angular version numbers have three parts: `major.minor.patch`. For example, version 7.2.11 indicates major version 7, minor version 2, and patch level 11.
* **Major releases** contain significant new features, some but minimal developer assistance is expected during the update. When updating to a new major release, you may need to run update scripts, refactor code, run additional tests, and learn new APIs.
* **Minor releases** contain new smaller features. Minor releases are fully backward-compatible; no developer assistance is expected during update, but you can optionally modify your apps and libraries to begin using new APIs, features, and capabilities that were added in the release. We update peer dependencies in minor versions by expanding the supported versions, but we do not require projects to update these dependencies.
* If you are updating within the **same major version,** then you can skip any intermediate versions and update directly to the targeted version. For example, you can update directly from 7.0.0 to 7.2.11.
* If you are updating from **one major version to another,** then we recommend that you **don't skip major versions.** Follow the instructions to incrementally update to the next major version, testing and validating at each step. For example, if you want to update from version 6.x.x to version 8.x.x, we recommend that you update to the latest 7.x.x release first. After successfully updating to 7.x.x, you can then update to 8.x.x.
See [Keeping Up-to-Date](guide/updating "Updating your projects") for more information about updating your Angular projects to the most recent version.
* **Next:** The release that is under active development. The next release is indicated by a release tag appended with the `next` identifier, such as `8.1.0-next.0`. For the next version of the documentation, see [next.angular.io](https://next.angular.io).
* **Beta:** A release that is under active development and testing. A Beta release is indicated by a release tag appended with the `beta` identifier, such as `8.0.0-beta.0`.
* **Release candidate:** A release that is feature complete and in final testing. A release candidate is indicated by a release tag appended with the `rc` identifier, such as version `8.1.0-rc`.
The next version of the documentation is available at [next.angular.io](https://next.angular.io). This includes any documentation for Beta or Release Candidate features and APIs.
This cadence of releases gives you access to new features as soon as they are ready, while maintaining the stability and reliability of the platform for production users.
Compatibility note: The primary goal of the backward compatibility promise is to ensure that changes in the core framework and tooling don't break the existing ecosystem of components and applications and don't put undue upgrade/migration burden on Angular application and component authors.
Sometimes "breaking changes", such as the removal of support for select APIs and features, are necessary to innovate and stay current with new best practices, changing dependencies, or changes in the (web) platform itself.
"破坏性变更"（比如移除特定的 API 和特性）有时候是必须的，比如创新、让最佳实践与时俱进、变更依赖关系甚至来自 Web 平台自身的变化。
* **Announcement:** We announce deprecated APIs and features in the [change log](https://github.com/angular/angular/blob/master/CHANGELOG.md "Angular change log"). Deprecated APIs appear in the [documentation](api?status=deprecated) with ~~strikethrough.~~ When we announce a deprecation, we also announce a recommended update path. For convenience, [Deprecations](guide/deprecations) contains a summary of deprecated APIs and features.
** 宣布弃用：** 我们会在[变更记录](https://github.com/angular/angular/blob/master/CHANGELOG.md "Angular change log")中宣布要弃用的那些 API 和特性。启用的 API 在[文档](api?status=deprecated)中会显示成带~~删除线~~的样式。当我们宣布一项弃用时，我们还会宣布一个建议的升级路径。为便于查找，我们在[弃用列表](guide/deprecations)中包含一个关于弃用 API 和特性的汇总表。
* **Deprecation period:** When an API or a feature is deprecated, it will still be present in the [next two major releases](#schedule). After that, deprecated APIs and features will be candidates for removal. A deprecation can be announced in any release, but the removal of a deprecated API or feature will happen only in major release. Until a deprecated API or feature is removed, it will be maintained according to the LTS support policy, meaning that only critical and security issues will be fixed.
**弃用阶段：** 当 API 或特性已弃用时，它在[接下来的两个主版本](#schedule)中仍然会存在。再往后，弃用的 API 和特性将会进入候选弃用状态。可能会在任何一次发布中宣布弃用，但是只会在主版本中移除已弃用的 API 或特性。除非已弃用的 API 或特性已被移除，否则我们仍然会根据 LTS 支持策略来维护它，也就是说，只会修复严重问题和安全问题。
* **npm dependencies:** We only make npm dependency updates that require changes to your apps in a major release.
In minor releases, we update peer dependencies by expanding the supported versions, but we do not require projects to update these dependencies until a future major version. This means that during minor Angular releases, npm dependency updates within Angular applications and libraries are optional.
Angular is a collection of many packages, sub-projects, and tools. To prevent accidental use of private APIs—and so that you can clearly understand what is covered by the practices described here—we document what is and is not considered our public API surface. For details, see [Supported Public API Surface of Angular](https://github.com/angular/angular/blob/master/docs/PUBLIC_API.md "Supported Public API Surface of Angular").
Angular 是很多包、子项目和工具的集合。为了防止你意外使用私有 API（这样你才能更清楚的理解哪些 API 会被这里所说的实践所覆盖），我们对公开 API 包含以及不包含哪些 API 进行了文档化。要了解详情，参见 [Angular 的公共 API](https://github.com/angular/angular/blob/master/docs/PUBLIC_API.md "Supported Public API Surface of Angular")。
Any changes to the public API surface will be done using the versioning, support, and depreciation policies describe above.
Angular Labs is an initiative to cultivate new features and iterate on them quickly. Angular Labs provides a safe place for exploration and experimentation by the Angular team.
Angular Labs projects are not ready for production use, and no commitment is made to bring them to production. The policies and practices that are described in this document do not apply to Angular Labs projects.
