What Is C#? A Beginner’s Guide to C# 14 and .NET 10

C# (pronounced “C sharp”) is Microsoft’s free, general-purpose programming language for building web apps, APIs, cloud services, desktop apps and Unity games. You write C#, and the .NET platform compiles and runs it on Windows, macOS and Linux.

In this tutorial, I’ll explain what is C# in plain English, then have you write and run your first program with the .NET 10 SDK. Then we’ll grow it one feature at a time.

What Is C#? The Language vs .NET vs Visual Studio

Beginners mix up three names, so here’s the split. C# is the language you type. .NET is the platform that runs it. Visual Studio and VS Code are just editors.

Name	What it is	You use it to
C#	Programming language (C# 14 is current)	Write the code
.NET	Free, open-source runtime, libraries and SDK	Compile and run the code
Visual Studio / VS Code	IDE / code editor (VS Code + C# Dev Kit)	Edit, debug and run projects

C# is strongly typed and object-oriented, with a garbage collector that frees memory for you. Its syntax looks like Java or JavaScript: semicolons, curly braces, if, for and switch statements in C#.

You’ll still hear “C#.NET” in job posts. It isn’t a separate language, just C# used with .NET.

What Is C# Used For in 2026?

Almost everything, and Blazor even covers browser UI. Here’s where I see C# used most:

You want to build	C# / .NET tool
Web apps and REST APIs	ASP.NET Core (MVC, Razor Pages, minimal APIs)
Interactive web UI in C#	Blazor
Cloud services	Azure SDK for .NET, Worker Services, Aspire
Desktop and mobile apps	WinForms, WPF, .NET MAUI
Games	Unity, MonoGame
AI apps	Microsoft Agent Framework, ML.NET

Current Versions: C# 14 and .NET 10 (LTS)

C# 14 shipped in November 2025 and is supported on .NET 10. .NET 10 is a Long Term Support release, released November 11, 2025 and supported until November 14, 2028.

LTS releases get three years of free patches; Standard Term Support releases get two. Both .NET 8 and .NET 9 reach end of support on November 10, 2026, so start new projects on .NET 10.

A Short History of the C# Language

C# was developed inside Microsoft; its principal inventors were Anders Hejlsberg, Scott Wiltamuth and Peter Golde. C# 1.0 shipped in January 2002 with Visual Studio .NET 2002, and Ecma standardized it as ECMA-334.

Later milestones: generics and anonymous methods in C# 2.0, LINQ in 3.0, async in 5.0 and records in 9.0. A new version now ships every November.

Write Your First C# Program on .NET 10

You don’t need a project file anymore: .NET 10 runs a single .cs file directly.

1. Install the .NET 10 SDK and check it with dotnet --version (mine printed 10.0.402).
2. Add VS Code and the C# Dev Kit; here’s how to download and install Visual Studio Code.
3. Save the code below as Hello.cs and run dotnet run Hello.cs.

// Hello.cs - my first C# program
string name = "Jenna";
Console.WriteLine($"Hello, {name}!");
Console.WriteLine($"Running on .NET {Environment.Version}");

Output:

Hello, Jenna!
Running on .NET 10.0.13

There’s no Main method or class here. Top-level statements let you start with the code itself, and $"..." drops values into a string.

When your code outgrows one file, run dotnet new console to get a project. I cover that in creating a console application in VS Code.

Key C# Language Features, Step by Step

Now let’s grow that first program. Each step is another small file in the same folder, run the same way.

Step 1: Types and var

Every variable in C# has a type the compiler knows before the program runs. var just lets the compiler figure it out:

using System.Globalization;
CultureInfo.CurrentCulture = new CultureInfo("en-US");

string city = "Austin";      // text
int orders = 42;             // whole number
decimal total = 1249.50m;    // money: use decimal
var state = "TX";            // the compiler infers string

Console.WriteLine($"{city}, {state}: {orders} orders, {total:C}");
Console.WriteLine($"state is a {state.GetType().Name}");

Output:

Austin, TX: 42 orders, $1,249.50
state is a String

Assign a number to that string, and the build fails before anything runs:

var state = "TX";
state = 5;   // a string variable can't hold an int

Build error:

C:\DotNetDemo\WhatIsCSharpDemo\TypeError.cs(2,9): error CS0029: Cannot implicitly convert type 'int' to 'string'

That early error is a big reason teams like C#. For the full list of types, see data types in C# and variables in C#.

Step 2: Classes and Records

A class bundles data with behavior. A record is a short way to declare data that compares by value and prints nicely:

var jenna = new Customer("Jenna Moore", "Seattle", "WA");
var moved = jenna with { City = "Spokane" };   // copy with one change
Console.WriteLine(moved);
Console.WriteLine($"Same data? {jenna == new Customer("Jenna Moore", "Seattle", "WA")}");

var cart = new Cart();
cart.Add(3);
Console.WriteLine($"Cart has {cart.Items} items");

// record: data with value equality and a readable ToString
record Customer(string Name, string City, string State);

// class: data + behavior
class Cart
{
    public int Items { get; private set; }
    public void Add(int quantity) => Items += quantity;
}

Output:

Customer { Name = Jenna Moore, City = Spokane, State = WA }
Same data? True
Cart has 3 items

Notice jenna == new Customer(...) is True because the data matches. Classes, inheritance and interfaces are covered in my OOP concepts in C# guide.

Step 3: LINQ Queries

LINQ lets you filter, group and sum a collection in a few readable lines instead of nested loops. Here I total sales by US state:

using System.Globalization;
CultureInfo.CurrentCulture = new CultureInfo("en-US");

List<Sale> sales =
[
    new("Ryan Carter", "TX", 1200m), new("Chloe Brady", "CA", 950m),
    new("Jenna Moore", "WA", 1430m), new("Zoe Ng", "TX", 610m),
    new("Ethan Rodriguez", "CA", 2075m),
];

var byState = sales.GroupBy(s => s.State)
                   .Select(g => new { State = g.Key, Total = g.Sum(s => s.Amount) })
                   .OrderByDescending(x => x.Total);

foreach (var row in byState)
    Console.WriteLine($"{row.State}: {row.Total:C0}");

Console.WriteLine($"Top rep: {sales.MaxBy(s => s.Amount)!.Rep}");

record Sale(string Rep, string State, decimal Amount);

Output:

CA: $3,025
TX: $1,810
WA: $1,430
Top rep: Ethan Rodriguez

The same methods work on arrays and lists. My guides to C# arrays and List in C# go deeper.

Step 4: async and await

Web apps spend most of their time waiting on databases and APIs. async and await wait without blocking a thread:

string[] results = await Task.WhenAll(
    CheckStockAsync("Seattle", 300),
    CheckStockAsync("Denver", 200),
    CheckStockAsync("Boston", 100));

foreach (string line in results) Console.WriteLine(line);

static async Task<string> CheckStockAsync(string store, int delayMs)
{
    await Task.Delay(delayMs);   // stands in for a web call
    return $"{store}: in stock";
}

Output:

Seattle: in stock
Denver: in stock
Boston: in stock

The three checks run at the same time, and WhenAll returns the results in the order you started them.

Step 5: Pattern Matching

A switch expression picks a result by the shape of the data. This one prices shipping by state and weight:

var parcels = new[] { ("TX", 2), ("CA", 12), ("AK", 4), ("NY", 0) };
foreach (var (state, pounds) in parcels)
    Console.WriteLine($"{state} {pounds,2} lb -> {Ship(state, pounds)}");

static string Ship(string state, int pounds) => (state, pounds) switch
{
    (_, <= 0)          => "invalid weight",
    ("AK" or "HI", _)  => "air, $24.99",
    (_, > 10)          => "freight, $14.99",
    _                  => "ground, $5.99",
};

Output:

TX  2 lb -> ground, $5.99
CA 12 lb -> freight, $14.99
AK  4 lb -> air, $24.99
NY  0 lb -> invalid weight

What’s New in C# 14?

C# 14 adds extension members, the field keyword, null-conditional assignment, implicit span conversions and more. Here are three you’ll use early:

var order = new Order { Zip = "  98101 " };
Console.WriteLine($"Zip: '{order.Zip}'");
Console.WriteLine($"Blank note? {"   ".IsBlank}");

Order? missing = null;
missing?.Zip = "10001";      // C# 14: skipped because missing is null
Console.WriteLine($"Still null: {missing is null}");

class Order
{
    // C# 14: 'field' is the compiler-made backing field
    public string Zip { get; set => field = value.Trim(); } = "";
}

static class TextExtensions
{
    extension(string text)   // C# 14: extension members
    {
        public bool IsBlank => string.IsNullOrWhiteSpace(text);
    }
}

Output:

Zip: '98101'
Blank note? True
Still null: True

field trimmed the zip code without a hand-written backing field, and IsBlank is an extension property. C# 14 also allows partial constructors, which pairs with partial classes in C#.

C# vs Java vs Python vs JavaScript: Which Language?

All four are good choices. Here’s how I’d compare them for a beginner:

	C#	Java	Python	JavaScript
Typing	Static	Static	Dynamic	Dynamic (TypeScript adds static)
Runs on	.NET	JVM	Interpreter	Browser, Node.js
Strongest at	Web APIs, Azure, desktop, Unity	Enterprise back ends, Android	Data, AI, scripting	Front-end web

If you know Java, C# will feel familiar within a week. From Python, static types take some getting used to.

Why Do Companies Use .NET for Web Applications?

Here are the reasons that still hold up in 2026, checked against Microsoft’s docs:

• Free and open source: .NET is MIT-licensed and a .NET Foundation project, with no license fee.
• Cross-platform: one ASP.NET Core app runs on Windows, Linux and macOS.
• Several languages: C#, F# and Visual Basic all run on .NET.
• Libraries and support: NuGet packages save code, and patches ship monthly on Patch Tuesday.

One correction to older articles: Code Access Security isn’t supported on modern .NET. Use OS boundaries like containers instead.

Interviewers ask about this, so read my .NET Core interview questions and answers.

Is C# a Good Language to Learn for a US Job?

I think so, especially if you’re targeting companies that run on Azure. Banks, insurers, healthcare, government contractors and game studios all hire C# developers.

Job titles to search include .NET developer, C# developer, ASP.NET Core developer and Unity developer. Before interviews, practice with these C# interview questions for freshers.

Your C# Learning Path: Where to Go Next

Write a tiny program every day for two weeks, then pick one workload, usually ASP.NET Core. Every tutorial I’ve written lives in the C# .NET tutorials section.

Ready for the next step? These four fill in the basics:

• Loop through data with the for loop
• Store key-value pairs in a Dictionary
• Define contracts with interfaces
• Write reusable methods in C#

Frequently Asked Questions