Polyfill
A polyfill is a piece of code (usually JavaScript) that provides modern functionality on older browsers that do not natively support it. It mimics the behavior of newer web APIs or features, allowing developers to use them consistently across different browser environments. Polyfills are essential for ensuring backward compatibility in web development.
Developers should use polyfills when building web applications that need to support older browsers (e.g., Internet Explorer) or when adopting new JavaScript features before they are widely available. This is crucial for maintaining functionality and user experience across diverse browser versions, such as in enterprise or legacy systems where users may not update their browsers regularly. Polyfills enable progressive enhancement by allowing the use of modern APIs while gracefully degrading for unsupported environments.