# Library guidance

This guidance provides recommendations for developers to create high-quality .NET libraries. This documentation focuses on the what and the why when building a .NET library, not the how.

Aspects of high-quality .NET libraries:

• Inclusive - Good .NET libraries strive to support many platforms, programming languages, and applications.
• Stable - Good .NET libraries coexist in the .NET ecosystem, running in applications built with many libraries.
• Designed to evolve - .NET libraries should improve and evolve over time, while supporting existing users.
• Debuggable - .NET libraries should use the latest tools to create a great debugging experience for users.
• Trusted - .NET libraries have developers' trust by publishing to NuGet using security best practices.

## Types of recommendations

Each article presents four types of recommendations: Do, Consider, Avoid, and Do not. The type of recommendation indicates how strongly it should be followed.

You should almost always follow a Do recommendation. For example:

✔️ DO distribute your library using a NuGet package.

On the other hand, Consider recommendations should generally be followed, but there are legitimate exceptions to the rule and you shouldn't feel bad about not following the guidance:

✔️ CONSIDER using SemVer 2.0.0 to version your NuGet package.

Avoid recommendations mention things that are generally not a good idea, but breaking the rule sometimes makes sense:

❌ AVOID NuGet package references that demand an exact version.

And finally, Do not recommendations indicate something you should almost never do:

❌ DO NOT publish strong-named and non-strong-named versions of your library. For example, Contoso.Api and Contoso.Api.StrongNamed.