What is C#?

C# (pronounced "C sharp", like the musical note) was created at Microsoft in 2000 by a team led by Anders Hejlsberg — one of the most influential language designers alive (he later co-created TypeScript, too).

The name is a music joke: in musical notation, a ♯ (sharp) raises a note a half-step. C# was pitched as a step up from C — and the # symbol even looks like four little + signs, one-upping C++.

What runs on C# today:

If your goal is making games or getting a job in the Microsoft/.NET world, C# is the language.

Let's untangle the name soup, because C, C++, and C# are three different languages:

| Language | Born | One-line summary |
|---|---|---|
| C | 1972 | Small, low-level, manual memory management |
| C++ | 1985 | C plus objects and much more — maximum control and speed |
| C# | 2000 | Modern, safe, garbage-collected — productivity first |

C# borrowed C-family syntax (braces, semicolons, if, for), so code looks related — but C# manages memory for you, checks your types strictly, and catches far more mistakes at compile time.

C#'s closest relative is actually Java: both compile to a portable format (IL / bytecode), both run on a managed runtime, both are strongly typed and object-oriented. If you ever read Java code, you'll find it eerily familiar — and this course will occasionally point out the few places where C# deliberately does things differently (usually more conveniently).

Like Java, C# is strongly typed — and that's great news for learning.

Every piece of data in C# has a declared type: whole number, decimal number, text, true/false… and the compiler verifies before the program runs that you use every value consistently. Try to store text where a number belongs, and the program simply won't compile.

What strictness buys you:

1. Mistakes surface immediately — at compile time with a line number, not as weird behavior at 2 AM.
2. Code documents itself — every variable announces what kind of data it holds.
3. Your tools get superpowers — because types are known, editors can autocomplete almost everything you type.

C# then layers on comforts Java learners envy: properties, string interpolation, var, expression-bodied methods — all coming up in this course. Strict where it matters, convenient everywhere else. That's C#'s personality in one sentence.

Here's a complete C# program. Don't memorize it — the next lesson dissects every line.

A preview of the pieces:

Run it, and the screen shows Hello, World! — the traditional first program in every language.