What is a Container widget in Flutter and what are its main properties?

Container — a convenient widget that can be used to add padding, margin, borders, background, and transformations to other widgets.

Main properties:

• alignment: Aligns the child widget within the container.
• padding: Internal spacing between the container's border and its content.
• color: Background color of the container.
• decoration: Allows setting more complex decorations such as gradients, shadows, rounded corners, and background images. When using decoration, the color property cannot be used separately.
• foregroundDecoration: Decoration drawn over the child widget.
• width: Width of the container.
• height: Height of the container.
• constraints: Additional size constraints for the container.
• margin: External spacing around the container.
• transform: Applies a transformation to the container and its content.
• child: The widget that is a child of the container.

Example usage:

Container(
  padding: const EdgeInsets.all(16.0), // Internal padding
  margin: const EdgeInsets.symmetric(vertical: 10.0), // External margin
  decoration: BoxDecoration( // Decoration with background color and rounded corners
    color: Colors.blue,
    borderRadius: BorderRadius.circular(10.0),
  ),
  child: const Text( // Child widget
    'Hello, Container!',
    style: TextStyle(color: Colors.white),
  ),
);