Shim

A shim is a code snippet enabling modern web features to function within older programming or browsing environments. Distinct from a polyfill — a specific type of shim that introduces non-native functionality to a web browser — shims allow newer web features to operate within outdated browsers.

As web browsers and applications evolve, shims address the compatibility issues that older browsers often encounter due to their lack of native support for recent web features, such as HTML5, CSS3, and JavaScript APIs.

Web developers leverage shims to ensure broad interoperability, making their applications accessible across various devices and browser versions. They help businesses appeal to a wider audience, guaranteeing seamless functionality regardless of the user’s technical setup.

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