How do I bold (or format) a piece of text within a paragraph?

How can I have a line of text with different formatting?

e.g.:

Hello World

You should use the RichText widget.

A RichText widget will take in a TextSpan widget that can also have a list of children TextSpans.

Each TextSpan widget can have a different TextStyle.

Here is the example code to render: Hello World

var text = RichText(
  text: TextSpan(
    // Note: Styles for TextSpans must be explicitly defined.
    // Child text spans will inherit styles from parent
    style: const TextStyle(
      fontSize: 14.0,
      color: Colors.black,
    ),
    children: <TextSpan>[
      TextSpan(text: 'Hello'),
      TextSpan(text: 'World', style: const TextStyle(fontWeight: FontWeight.bold)),
    ],
  ),
);