Skills on AI 459 skills

.NET Programming

Use when asked about the .NET platform/runtime and tooling itself — the CLR, the base class library, project SDKs and NuGet, cross-language interop — as distinct from any one .NET language (see c-sharp-programming) or framework (see blazor-programming).

.NET is a free, cross-platform, open-source developer platform — the runtime (CLR), a large standard library (the base class library, BCL), and tooling (the dotnet CLI, project SDKs, NuGet) that multiple languages (C#, F#, Visual Basic) compile down to and share. This skill covers the platform itself; C# Programming covers the dominant language on top of it.

The runtime and cross-language interop

.NET languages compile to a shared intermediate language (IL), executed by the Common Language Runtime (CLR) — a JIT-compiled, garbage-collected runtime. Because every .NET language targets the same IL and type system (the Common Type System, CTS), a library written in F# can be consumed directly from C# and vice versa, with no interop layer needed.

Project SDKs and the dotnet CLI

dotnet new webapi -n MyApi         # scaffold a new project from a template
dotnet build                        # compile
dotnet run                          # build + run
dotnet test                         # run tests
dotnet publish -c Release           # produce a deployable, self-contained or framework-dependent output
dotnet add package Newtonsoft.Json  # add a NuGet dependency

A .csproj (or .fsproj/.vbproj) file declares the target framework (e.g. net9.0), dependencies, and build settings in a lean XML format — much smaller than the older .NET Framework-era project format, since modern SDK-style projects infer file inclusion by convention rather than listing every file explicitly.

NuGet

NuGet is .NET's package manager — packages are distributed as .nupkg files (referenced by ID and version in the project file), resolved and restored via dotnet restore (implicit in build/run), with a packages.lock.json optionally pinning exact resolved versions for reproducible builds.

Base class library (BCL)

The BCL is .NET's standard library — collections, LINQ, I/O, networking, threading/async primitives, and more — available identically across every .NET language and (for the cross-platform, modern .NET, as opposed to the Windows-only legacy .NET Framework) every supported OS.

Common pitfalls

  • Confusing .NET Framework (legacy, Windows-only) with modern .NET (.NET 5+, cross-platform) — they share a name and much of the BCL's shape, but are different runtimes with different support and platform reach; check which one a specific project or tutorial targets.
  • Mixing target framework versions across a solution without checking compatibility — a library targeting a newer target framework moniker (TFM) than a consuming project can fail to build or load.
  • Not committing a lock file for applications — without packages.lock.json, a dotnet restore can resolve to different transitive dependency versions over time as new compatible versions are published.
  • Treating the dotnet CLI templates as fixed — dotnet new list shows the actual set of installed templates, which varies by installed SDKs and workloads; don't assume a template exists without checking.

Learn more

View dot-net-programming/SKILL.md on GitHub