A User Script is a small program that modifies the behavior or appearance of a website. These scripts are typically written in JavaScript and can be used to enhance user experience by adding new features, changing layouts, or automating repetitive tasks. Users can install these scripts through browser extensions like Tampermonkey or Greasemonkey. User Scripts are often created by individuals in the online community who want to share their customizations. They can be found on various platforms, such as OpenUserJS or GreasyFork, where users can browse, download, and contribute their own scripts to improve web browsing for everyone.