The following code uses many of Dart’s most basic features:

// Define a function.
void printInteger(int aNumber) {
print(‘The number is $aNumber.’); // Print to console.
}

// This is where the app starts executing.
void main() {
var number = 42; // Declare and initialize a variable.
printInteger(number); // Call a function.
}

Here’s what this program uses that applies to all (or almost all) Dart apps:

// This is a comment.

A single-line comment. Dart also supports multi-line and document comments. For details, see Comments.

void

A special type that indicates a value that’s never used. Functions like printInteger() and main() that don’t explicitly return a value have the void return type.

int

Another type, indicating an integer. Some additional built-in types are String, List, and bool.

42

A number literal. Number literals are a kind of compile-time constant.

print()

A handy way to display output.

'...' (or "...")

A string literal.

$variableName (or ${expression})

String interpolation: including a variable or expression’s string equivalent inside of a string literal. For more information, see Strings.

main()

The special, required, top-level function where app execution starts. For more information, see The main() function.

var

A way to declare a variable without specifying its type. The type of this variable (int) is determined by its initial value (42).

Yes. For programs targeting devices (mobile, desktop, server, and more), Dart Native includes both a Dart VM with JIT (just-in-time) compilation and an AOT (ahead-of-time) compiler for producing machine code.

Flutter is a sample framework that uses Dart’s native compilation capability to produce fast native apps.

Google Ads, AdSense, AdMob, and the Google Assistant all use Dart. A significant portion of Google’s revenue flows through these apps. Inside or outside of Google, every Flutter app uses Dart.

Yes! You can build an Android app that also works on iOS from a single codebase using Flutter, which is powered by the Dart platform.

You can find many packages on the pub.dev site a service for hosting packages of Dart code. Use the pub command to package your code and upload to the site.

Yes, Dart 2 is statically typed. For more information, read about Dart’s type system.

With its combination of static and runtime checks, Dart has a sound type system, which guarantees that an expression of one type cannot produce a value of another type. No surprises!

Even with type-safe Dart, you can annotate any variable with dynamic if you need the flexibility of a dynamic language. The dynamic type itself is static, but can contain any type at runtime. Of course, that removes many of the benefits of a type-safe language for that variable.

Dart has some similarities with Java. See the Intro to Dart for Java Developers codelab for examples of some of the differences between Dart and Java.