// include the IsMobile library require_once('path/to/IsMobile.php'); // check if the visitor is using a mobile phone if (IsMobile::isMobile()) { // code to display mobile-specific content } else { // code to display desktop-specific content }There are several package libraries that include the IsMobile utility, such as `mobiledetect/mobiledetectlib` and `serbanghita/mobile-detect`. These libraries not only include the IsMobile utility, but also additional features for detecting various mobile devices and operating systems, as well as providing additional information on the visitor's browser and capabilities.