.NET

The cross-platform runtime and tooling.

.NET is taught here in 14 lessons, running from .NET SDK and project files through to Diagnostics and observability in production. Each lesson takes one topic, shows the working code, and links onward to the next, so the course can be read straight through in order.

Lessons

1. .NET SDK and project filesWhat the SDK actually installs, how an SDK-style project file describes a build, and how to pin a repository to one SDK version.
2. The dotnet CLI workflowSolution and project scaffolding, package management, and the build, test, watch and format loop you actually live in.
3. Publishing and deploymentFramework-dependent versus self-contained output, containerising a service, and the trimming and AOT trade-offs you must measure.
4. What .NET is: runtime, libraries and support policyThe CLR, the base class library and the release cadence, plus how to choose between .NET and .NET Framework for a service that has to live for years.
5. Project types, target frameworks and multi-targetingChoosing the right project type and the right target framework is the cheapest architectural decision you will make, and the hardest to undo.
6. NuGet and dependency managementVersion ranges, transitive dependencies, central package management and a restore you can reproduce on any machine.
7. Dependency injection and the generic hostLifetimes decide correctness, not just performance: a captured scoped service inside a singleton is a real bug that only shows up in production.
8. Configuration, options and loggingThe configuration stack layers, the options pattern with validation, and structured logging that is worth reading when something breaks.
9. Asynchronous programming with async and awaitAsync is not about threads, it is about not blocking one. The failure modes are all about blocking, fire-and-forget and lost cancellation.
10. JSON serialisation with System.Text.JsonThe built-in serialiser is fast and allocation-light, and source generation removes its startup cost and its reflection dependency.
11. Testing .NET codexUnit setup, fixtures, the assertions that describe intent, and choosing what to mock so the tests stay useful.
12. Writing and publishing NuGet librariesPackage metadata, symbol packages, semantic versioning and how to validate a package before anyone depends on it.
13. Performance: allocation, Span and benchmarkingMeasure first, then reduce allocations on the hot path with Span and pooling rather than rewriting code on intuition.
14. Diagnostics and observability in productionCounters, traces and dumps answer different questions. Knowing which tool fits a symptom is most of production debugging.

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