User Script Managers are browser extensions that allow users to customize their web experience by running small pieces of JavaScript code, known as user scripts. These scripts can modify the appearance and functionality of websites, enabling users to add features, remove ads, or automate repetitive tasks. Popular User Script Managers include Tampermonkey and Greasemonkey. By installing a User Script Manager, users can easily manage and organize their scripts, enabling or disabling them as needed. This flexibility allows for a personalized browsing experience tailored to individual preferences, enhancing usability and efficiency on the web.