Dart คืออะไร และคุณสมบัติหลักของมันสำหรับ Flutter มีอะไรบ้าง?

Dart = Google's language for Flutter (and more):
  → OBJECT-ORIENTED, statically typed (with type inference)
  → familiar C-style/Java-like syntax (easy for many developers to pick up)
  → designed for UI development; compiles to native code (mobile) and JavaScript (web)

// variables and types (statically typed with inference)
var name = 'Ann';          // inferred String
int age = 30;              // explicit type
final pi = 3.14;          // final (can't reassign)
const max = 100;          // compile-time constant

// null safety — types are non-nullable by default
String name;              // can't be null
String? nickname;         // nullable (the ? allows null) — prevents null errors

// functions (including arrow syntax)
int add(int a, int b) => a + b;

// classes
class Person {
  final String name;
  Person(this.name);                // concise constructor
}