Chapter 1: Introduction to C# and .NET

1. What is C#? (Simple & Clear Explanation)

C# (pronounced “C Sharp”) is a modern, powerful, and very popular programming language created by Microsoft.

Think of it like this:

• C → is the grandfather (very old, powerful but tricky)
• C++ → is the father (more features, but still complicated)
• C# → is the cool, modern son — easier to use, safer, and does almost everything the parents can do (and more!)

C# was designed to be:

• Object-oriented (we’ll talk about this a lot later — it’s super important!)
• Type-safe (helps you avoid silly mistakes)
• Simple yet powerful
• Beautiful syntax (many developers say it’s one of the nicest-looking languages)

2. Brief History of C# (Just the Important Parts)

• 2000 — Microsoft announces C# at the Professional Developers Conference (PDC). Anders Hejlsberg (the creator of Turbo Pascal & Delphi) leads the team.
• 2002 — C# 1.0 is released together with .NET Framework 1.0. It was basic but already very good!
• 2005 — C# 2.0 — Generics arrive (huge for performance and safety)
• 2007 — C# 3.0 — LINQ (one of the biggest game-changers ever!)
• 2010 — C# 4.0 — Dynamic typing, named & optional parameters
• 2012 — C# 5.0 — async/await (made asynchronous programming beautiful)
• 2017 — C# 7.0 — Tuples, pattern matching, local functions
• 2019 — C# 8.0 — Nullable reference types, default interface methods
• 2021 — C# 10 — Global using directives, file-scoped namespaces
• 2022 — C# 11 — Raw string literals, required members
• 2023 — C# 12 — Primary constructors, collection expressions
• 2024 — C# 13 — Enhanced params collections, new lock object, partial properties, field keyword (preview in VS 17.12+)
• 2025 — C# 14 — Released with .NET 10 (November 2025) — brings even more modern features like extension members, user-defined compound assignment operators, and more performance & productivity improvements

As of January 2026, the latest stable version is C# 14 (released with .NET 10 in November 2025). C# 14 is what most new projects should use today!

3. What is the .NET Ecosystem? (2026 Edition)

.NET is the platform (like the house) where C# (the language) lives and works.

Think of .NET as a big toolbox that gives C# all the power to:

• Run fast
• Work on Windows, macOS, Linux
• Build web apps, mobile apps, desktop apps, games (Unity), cloud services, AI apps, IoT, etc.

Two Big Branches (Very Important!)

Current .NET Versions (as of January 2026)

Recommendation for 2026: Start new projects with .NET 10 + C# 14 (It’s the most modern, fastest, and supported for the longest time!)

4. Setting Up Your Environment (Step-by-Step – Super Detailed)

You have two excellent choices in 2026:

Option A: Visual Studio 2026 (Recommended for Beginners – Full Power)

1. Go to: https://visualstudio.microsoft.com/downloads/
2. Download Visual Studio 2026 Community (it’s free for individuals, students, open-source, small teams!)
3. Run the installer
4. In the workloads screen, select:
   • .NET desktop development
   • ASP.NET and web development (if you want web apps)
   • .NET Multi-platform App UI development (for mobile/desktop with .NET MAUI)
   • Game development with Unity (optional)
5. Click Install (it will download ~5–10 GB depending on what you choose)
6. After installation → Open Visual Studio → Create a new project → Choose Console App (.NET) → Select .NET 10.0 → Done!

Option B: Visual Studio Code + .NET SDK (Lightweight & Free Forever)

1. Download & install Visual Studio Code: https://code.visualstudio.com/
2. Install .NET 10 SDK:
   • Go to: https://dotnet.microsoft.com/en-us/download/dotnet/10.0
   • Download the SDK (not just runtime) for your OS
   • Install it (very small ~200 MB)
3. Open VS Code → Go to Extensions (Ctrl+Shift+X) → Search & install:
   • C# Dev Kit (official Microsoft extension — includes IntelliSense, debugging, testing, etc.)
   • C# (the base language support)
4. Open a folder → Create a new console app:
   Bash

   PHP

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   dotnet new console -o MyFirstApp cd MyFirstApp code .

5. Press F5 to run — magic! 🚀

Quick Test – Your First “Hello World”

Create a file Program.cs (or it’s already there if you used dotnet new):

Run it:

• In Visual Studio → F5
• In VS Code → F5 or terminal: dotnet run

You should see:

Congratulations! 🎉 You just ran your first C# program!

Homework for Next Class

1. Install either Visual Studio 2026 or VS Code + .NET 10 SDK
2. Create and run the Hello World program above
3. Change the message to something fun about yourself (e.g., “Hi, I’m learning C# and loving it! 😍”)
4. Run it again and feel proud!

In the next chapter, we’ll talk about Variables, Data Types, and start writing real code. Get ready — it’s going to be fun!