Font-weight

The   property is used in CSS and certain HTML elements. It is used to specify the weight or boldness of the text, or font.

Values
HTML example:

That will produce: Normal font.

This is font with the  value applied: Bold font.

This is font with the  value applied: Lighter font.

This is font with the  value applied: Bolder font.

This is font with the  value applied: 100 font.

This is font with the  value applied: 900 font.

CSS example: