Less (Leaner Style Sheets) is a popular open-source CSS preprocessor that extends the capabilities of CSS with dynamic behaviors such as variables, mixins, operations, and functions. Available at https://lesscss.org, Less facilitates more maintainable, readable, and extendable CSS by utilizing a simpler syntax that reduces repetition and enhances the functionality of stylesheets. Essentially, it allows developers to write CSS in a programming construct, which can then be compiled into standard CSS output for browser use. This tool is particularly valuable for developers looking to streamline their styling workflow and maintain large-scale style sheets more effectively.