A WordPress theme is a pre-existing design or “skin” that can be applied to a WordPress site. A theme instantly changes a site’s appearance, without affecting its programming. Themes often come with plugins that add features and functionality. Some themes are designed for specific industries or types of content, such as e-commerce, food and drink, photography, and news.
Responsive themes dynamically adjust to a device’s screen size and resolution. They change the sizes and layout of components to optimize the site for mobile users. Administrators can choose from a wide variety of responsive themes.
Since WordPress is an open-source platform; it allows changes that can be made to existing themes; giving designers and developers more freedom in creating custom user experiences across the WordPress platform.