1) Mobile devices have replaced dedicated devices like MP3 players and cameras, and some users prefer using apps over visiting websites. 2) As mobile usage grows, websites need to ensure their content is compatible with mobile interfaces and devices to stay competitive, including using responsive design and mobile apps. 3) Technologies like HTML5 meta tags, CSS media queries, and redirecting based on browser can help make websites accessible across devices, though some sites with flash content remain difficult to view on mobile. Major sites like Google, YouTube, and eBay generally work well on mobile.