Hello World and Project Structure

Writing "Hello, World!" in C# has gotten dramatically simpler over the years. Early C# required an explicit namespace, class, and a static void Main(string[] args) method just to print one line. Since C# 9 (2020) and the top-level statements feature, a console app's entire logic can live directly in Program.cs with no boilerplate wrapper, while the compiler generates the class and Main method behind the scenes. Understanding both the modern minimal form and what it compiles down to is essential, because most real-world codebases still mix both styles depending on their age and conventions.

Running dotnet new console produces two key files: Program.cs, containing your executable code, and a .csproj (MSBuild project) file, an XML document describing the project's target framework, output type, and package references. The .csproj is deliberately terse in modern .NET — the SDK-style project format infers sensible defaults (like including all .cs files in the folder automatically) so you rarely need to hand-edit it for a simple app.

Top-level statements are syntactic sugar: the compiler still generates an internal Program class with a Main method, but you write only the statements that would go inside it, directly at the top of the file. This is ideal for scripts, small tools, and tutorials. Larger applications, or ones needing an explicitly named entry-point class (for example, to reference Program from a test project), often still use the traditional explicit form.