Service workers are a key feature in modern web development that enable websites to provide better user experiences, especially for international markets with unreliable internet. Pinterest is using service workers to cache JavaScript files and deliver notifications, showcasing their potential for improving performance. Additionally, the conversation highlights the value of service workers in serving offline experiences, allowing users to access content even without an active internet connection. The episode also reveals Pinterest's ambitious vision to leverage service workers to deliver a comprehensive offline experience, further solidifying their importance in web development.