Online Supplementary Link-4 (OSL-4) is a web-based system for displaying content from the World Wide Web in a more organized and efficient manner. OSL-4 is a two-way link between webpages that can be used to display supplementary content, such as images, videos, or web-articles. Using OSL-4, the content is displayed in a interactive and engaging way, allowing users to access additional information about a webpage without having to visit the webpage directly. This makes it easier for users to find information quickly without having to navigate through a long list of links. Additionally, it can be used to create web-pages that are more visually appealing and interactive, bringing more visitors to a website. The system is also highly customizable, allowing web-designers to display content in a variety of ways, and incorporate other features such as social media integration and other multimedia content. Overall, OSL-4 is an easy-to-use and effective system for displaying web-based content. It is an important tool for web-designers and offers benefits for users as well. It can help create websites that are visually appealing and engaging, helping to draw more visitors to a website and provide additional information.