A WordPress theme changes the design of your website, often including its layout. Changing your theme changes how your site looks on the front-end, i.e. what a visitor sees when they browse to your site on the web. There are thousands of free WordPress themes in the WordPress.org Theme Directory, though many WordPress sites use custom themes.
Themes take the content and data stored by WordPress and display it in the browser. When you create a WordPress theme, you decide how that content looks and is displayed. There are many options available to you when building your theme. For example:
WordPress themes are incredibly powerful. But, as with every web design project, a theme is more than color and layout. Good themes improve engagement with your website’s content in addition to being beautiful.