Increase or decrease how bold or light a font appears with CSS

The font-weight property provides the functionality to specify how bold a font is. Possible values could be normal, bold, bolder, lighter, 100, 200, 300, 400, 500, 600, 700, 800, 900.

      <p style = "font-weight:bold;">This font is bold.</p>
      <p style = "font-weight:bolder;">This font is bolder.</p>
      <p style = "font-weight:400;">This font is 500 weight.</p>