General · EdgepediaSeptember 17, 20268 min read

.NET

.NET is a cross-platform, open-source developer platform from Microsoft, used to build web, mobile, desktop, cloud, and game applications. Its execution model is standardized in ECMA-335, which defines the Common Language Infrastructure (CLI), a specification under which applications written in multiple high-level languages run in different system environments without rewriting for each environment's characteristics¹. The platform is available on GitHub under the MIT license².

Key fact	Detail
Release cadence	Major versions ship annually in November; even-numbered releases (.NET 8, .NET 10) are Long Term Support (LTS), odd-numbered (.NET 9, .NET 11) are Standard Term Support (STS)²
Support length	LTS releases are supported a minimum of 3 years; STS releases a minimum of 24 months, each or 12 months after a successor ships²
Current LTS	.NET 10, released November 11, 2025, end of support November 14, 2028³
License	MIT license, source on GitHub²
Ecosystem size	Over 478,000 packages on NuGet with more than 800 billion downloads⁴
Adoption	ASP.NET Core is tracked in the Stack Overflow Developer Survey⁵
Execution model	Source typically compiles to Common Intermediate Language (CIL), which is commonly converted to native code by a just-in-time compiler at runtime⁶

What .NET is

The CLR provides core system services including class loading, compilation, exception handling, garbage collection, and security⁷. Managed code running on it receives garbage collection, security, interoperability with unmanaged code, cross-language debugging support, and enhanced deployment and versioning support⁶.

To support building and running many different source languages together, the CLR offers a common type system, an intermediate language, and an environment for dynamic execution.⁸ At the original launch Microsoft shipped four languages, Visual Basic, C++, C#, and J#, with industry partners supporting in excess of 20 languages on the runtime⁷. Today the principal Microsoft languages are C# and F#: C# 14 and F# 10 ship with .NET 10, and C# ranks in the top 5 languages in the 2025 GitHub Octoverse report⁴.

History and unification

The .NET ecosystem launched in 2002 with the .NET Framework for Windows applications⁹. .NET Core was created so that .NET could be open source, cross platform, and used in more resource-constrained environments². Microsoft first announced .NET Core 5 in April 2014 at TechEd North America as a "cloud optimized" version of .NET, later renaming it ".NET Core"¹⁰. At the Connect(); event in November 2014 it delivered .NET Core 5 as a completely open-source stack under the MIT license, supported on Windows, Linux, and Mac, and contributed to the .NET Foundation¹⁰. Microsoft had already open-sourced the managed compilers for C#, VB, and F# as well as ASP.NET, and then announced that .NET Core itself would be open source, including the runtime and the framework libraries¹¹.

One runtime, two lineages. .NET Core and the .NET Framework share the garbage collector, the JIT, and types such as String and List, a subset-superset relationship². The .NET Core runtime is built from the same codebase as the .NET Framework CLR and includes the same GC and JIT (RyuJIT), but omits Application Domains and Code Access Security, and is delivered via NuGet¹⁰. The modern .NET 5+ line continues from .NET Core; .NET 5.0 reached end of support on May 10, 2022, and .NET Core 3.1 on December 13, 2022¹².

The .NET Framework line remains Windows-bound: .NET Framework 4.8 will continue to be distributed with future releases of Windows, supported as long as the underlying Windows version is supported³. Versions older than 4.6.2 have reached end of support².

How the runtime works

Compilers targeting the CLR typically translate source code into Common Intermediate Language (CIL), a CPU-independent instruction set that is commonly converted to native code by a just-in-time (JIT) compiler at application runtime⁶. The CLR supplies a JIT compiler for each supported CPU architecture, so the same CIL assemblies run on different machine architectures⁶.

On-demand compilation. Rather than converting all the CIL in an executable at once, the runtime compiles methods as needed during execution and stores the resulting native code in memory⁶. The JIT compiler is RyuJIT, evolved from the x86 jit32 JIT on .NET Framework and ported to all architecture and platform targets supported by .NET Core; it provides both just-in-time and ahead-of-time compilation services for the runtime¹³.

Tiered compilation. Tiered compilation lets the runtime substitute different compiled implementations of the same method during an application's lifetime to achieve higher performance¹⁴. Tier0 is whatever code can be made available most quickly to first run a method, generated with minimal optimizations for startup; once a method appears hot, higher-quality Tier1 code replaces it¹⁴. For methods precompiled in ReadyToRun images, the precompiled code serves as the Tier0 version, and the runtime may replace hot ReadyToRun code with jitted code that can exploit the exact loaded dependencies and CPU instruction support¹⁴. The stated goals are to improve the steady-state and startup performance of typical .NET Core workloads while minimizing regressions¹⁴.

Generics. In supporting parametric polymorphism, the CLR exploits the runtime's dynamic character: it specializes types just in time, shares code based on representation, and applies novel methods for creating and using run-time types efficiently.⁸ Ahead-of-time compilation of CIL has a research lineage as well: Microsoft Research's Bartok compiler compiled CIL to x86 code ahead-of-time, with most of its runtime and base class libraries written in C# itself¹⁵.

Workloads and frameworks

ASP.NET Core and Entity Framework Core ship as part of .NET releases and follow the lifecycle of the parent release².

.NET MAUI (Multi-platform App UI) lets developers create modern, natively compiled apps for iOS, Android, macOS, and Windows from one codebase, written in C# and XAML.³ MAUI was slated as a major part of .NET 7 with a limited version available earlier, twenty years after the platform's launch¹⁶. In the year before .NET 9, MAUI developer usage grew more than 30% to an all-time high¹⁷.

.NET Aspire targets cloud-native development: Aspire 13 ships with .NET 10 with major improvements for polyglot development, modern workflows, and enterprise deployment⁴.

By the numbers

The version and support picture as of the .NET 10 release:

Version	Released	Type	End of support
.NET 10	November 11, 2025	LTS	November 14, 2028³
.NET 9	November 12, 2024	STS	November 10, 2026³
.NET 8	November 14, 2023	LTS	November 10, 2026³
.NET 7		STS	May 14, 2024¹²
.NET 6		LTS	November 12, 2024¹²

With the extension of STS support from 18 to 24 months, both .NET 9 and .NET 8 reach end of support on November 10, 2026⁴.

Adoption figures place .NET among the most widely used server-side ecosystems. In the 2026 Stack Overflow Developer Survey, ASP.NET Core was used by 19.9% of respondents and ASP.NET (Framework) by 13.9%, against Node.js at 46.4% and React at 41.5%¹⁸. In the timeseries where ASP.NET Core was first tracked separately, its usage rose from 3.0% in 2024 to 4.5% in 2025 and 6.2% in 2026, while ASP.NET held at 12.9%, 14.2%, and 13.9% across those years¹⁸.

Performance and how it compares

Microsoft describes .NET 9 as its most performant release to date, with over 1,000 performance-related changes across the runtime, workloads, and languages; exceptions became 50% faster through adopting the same exception model used by Native AOT¹⁷.

In a peer-reviewed comparative study of back-end frameworks, .NET showed the best response times, followed closely by Node.js and Django REST Framework, but that improvement came with higher system resource consumption⁹.

Raw throughput figures from TechEmpower Round 23 (February 2025), as reported in a developer analysis, measured ASP.NET Core on .NET 9 at 27,530,836 requests per second in the plaintext benchmark versus Fastify (Node.js) at 1,175,038 and Express at 279,922, a 23.4x raw-throughput gap¹⁹. On a JSON workload with real work the gap narrows to about 3.0x: ASP.NET Core at 2,546,481 requests per second versus Fastify at 844,960¹⁹.

Recent developments

Two releases have shipped since .NET 8 in November 2023. .NET 9 (November 12, 2024) brought the 1,000-plus performance changes and the faster exception model noted above¹⁷. .NET 10 (November 11, 2025) is an LTS release supported for three years⁴.

Hardware acceleration. .NET 10 adds AVX10.2 support for cutting-edge Intel silicon and Arm64 SVE for advanced vectorization, with Arm64 write-barrier improvements reducing GC pause times by 8 to 20%⁴.

Support policy. STS support was extended from 18 to 24 months, a change that lengthens the usable life of odd-numbered releases such as .NET 9⁴.

Languages and tooling. C# 14 and F# 10 ship with .NET 10, and Aspire 13 arrives alongside it⁴.

Licensing, support, and governance

.NET is available on GitHub under the MIT license², and Microsoft supports .NET Core on Windows, Linux, and Mac¹⁰. Microsoft contributed .NET Core to the .NET Foundation as part of the open-source transition¹⁰.

The two product lines carry different support models. Modern .NET follows the annual November cadence with LTS and STS designations², while .NET Framework 4.8 is supported as a Windows component rather than as an independently versioned product³.

One date is reported differently across Microsoft's own sources: the support policy page lists .NET 10's end of support as November 14, 2028³, while the .NET 10 announcement says supported for three years until November 10, 2028⁴.

References

Topic: Encyclopedia › Technology and the built world › Computing and digital systems › Software and programming › Development tools and collaboration infrastructure › Frameworks, libraries, and APIs › Mobile and platform frameworks

Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 15, 2026 · Edited: Sep 30, 2026; Oct 15, 2026; Oct 25, 2026 · Last review: Oct 15, 2026

Notice something wrong?