Any WordPress theme can act as a parent theme.
If you’re using a third-party theme, and want to tweak it for your own project, it’s a much better practice to use a child theme than to hack the main theme, which exposes you to the risk of losing your changes when you update the theme to future versions.
To create a child theme, create a new theme, and at the beginning of its style sheet, add:
Theme Name: Twenty Fourteen Child
Theme URI: http://example.com/twenty-fourteen-child/
Description: Twenty Fourteen Child Theme
Author: John Doe