How to Extend the WordPress Customizer

Way back in 2013, the WordPress 3.4 Green release introduced the Customizer to the masses. If you’re up for a trip down memory lane, here’s the announcement post over on Make WordPress. Not without its fair share of naysayers, the Customizer looked to, and still does, bring accessibility and instant feedback to visual changes you make on your WordPress site. Its humbler beginnings focused on smaller things like changing your site background color or changing your site title, but to anyone who really understood what it represented, it meant WordPress users would have:
The ability to preview changes before making them go live on their site.
A foundation for plugin and theme developers to deliver settings and options according to WordPress best practices.
Needless to say, the underlying value of the Customizer has helped it navigate its teething pains and become a feature that is both meaningful and good to use.
In this post, we’re going to have a look at different ways anyone can leverage the power of the Customizer to extend their WordPress site. We’ll touch here and there on a few development techniques, but rather than give you play-by-play tutorials, we want
Source: https://managewp.org/articles/15215/how-to-extend-the-wordpress-customizer

source https://williechiu40.wordpress.com/2017/05/26/how-to-extend-the-wordpress-customizer/