Target Frameworks, TFMs, and .NET Standard

A target framework tells the .NET SDK which platform version and API surface your project is built for. The short name for that target is a target framework moniker, or TFM.

Original Microsoft Learn references: Target frameworks in SDK-style projects and .NET Standard.

A practical mental model

flowchart LR
    A["Project file"] --> B["Target framework"]
    B --> C["Available APIs and compatibility"]
    C --> D["Build and runtime behavior"]

Common examples

• net8.0, net9.0, and net10.0 target modern .NET versions.
• netstandard2.0 and netstandard2.1 describe shared API contracts for libraries.
• net48 targets .NET Framework 4.8.

Why it matters

The target framework controls which APIs are available, which runtime can execute the program, and which packages are compatible. A library can target more than one framework when it needs to support different consumers.

This means the target framework is not just metadata. It is a compatibility decision.

Single-targeting and multi-targeting

<PropertyGroup>
  <TargetFramework>net9.0</TargetFramework>
</PropertyGroup>

Multi-targeting uses TargetFrameworks with a semicolon-separated list.

<PropertyGroup>
  <TargetFrameworks>net8.0;net9.0</TargetFrameworks>
</PropertyGroup>

Multi-targeting is most common for libraries that need to support multiple consumer environments.

Where .NET Standard fits

.NET Standard is best understood as an API contract for libraries rather than as a runtime you run directly.

That distinction matters because learners often confuse these ideas:

• a runtime that executes applications
• a target framework that describes a platform version
• a shared API contract intended to improve library compatibility

Practical guidance

Choose a target framework based on:

• the environment where the application or library must run
• the APIs you need
• package compatibility requirements
• whether library consumers need broad support across platforms or older runtimes

Summary

• a TFM tells the SDK and tooling what platform the project targets
• target frameworks influence available APIs, compatible runtimes, and package support
• multi-targeting is mainly useful when one project must serve multiple consumer environments
• .NET Standard is a shared API contract, not a standalone runtime

Practice

Open a .csproj file and identify its target framework. Then check whether the installed SDK can build that target with dotnet --list-sdks.

As a second exercise, explain when a library might need multi-targeting and when a normal application usually does not.