C#

What C# is, where it runs today, and why it's no longer "just the Windows language."

Installing the .NET SDK and getting comfortable with the dotnet CLI before writing any C#.

Scaffolding, running, and understanding a minimal "Hello, World" console app.

Declaring variables and understanding the difference between value types and reference types in C#.

When var makes code cleaner, and why it doesn't make C# dynamically typed.

How C#'s nullable reference types and nullable value types help catch null-reference bugs before runtime.

Branching in C#, from classic if/else chains to the more concise switch expression syntax.

The four loop constructs C# offers, and when to reach for each one.

Using is, switch patterns, and property patterns to check shape and type, not just equality.

Method syntax, return types, parameters, and the difference between passing by value and by reference.

Giving parameters default values and calling methods with named arguments for clarity.

Defining classes, constructors, and creating instances — the foundation of object-oriented C#.

Why C# favors properties over public fields, and how auto-properties keep the syntax lightweight.

Extending classes with inheritance, and overriding behavior with virtual and override.

Defining contracts with interfaces, and why they're how C# achieves multiple-inheritance-like flexibility.

How C#'s record type gives you value-based equality and immutability with almost no boilerplate.

The core collection types -- List, Dictionary, HashSet -- and when to reach for each.

Querying and transforming collections declaratively with LINQ instead of hand-written loops.

Writing non-blocking code with async/await and understanding what Task actually represents.

Using try/catch/finally correctly, and knowing when an exception is the right tool at all.

A tour of ASP.NET Core's main application models and how Azure fits into the C# cloud story.

A closing checklist of habits that separate solid, idiomatic C# from code that merely compiles.