A single-page application is a web app that initially loads only one web page and then updates the content dynamically using JavaScript APIs. This allows users to interact with the website without page reloads. Thus, improving the performance of the application and giving users a seamless experience.
All necessary assets/codes are either loaded at the first load or are loaded dynamically as their requirement arises. Because most of the applications are rendered in the browser, this can result in poor SEO.