Suggest an editImprove this articleRefine the answer for “How does a postprocessor differ from a preprocessor (SASS/LESS)?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)**A postprocessor and a preprocessor** solve different tasks and work at different stages of CSS processing. **Key point:** a preprocessor generates CSS from an extended syntax before CSS exists, while a postprocessor modifies already-finished CSS without extending the language.Shown above the full answer for quick recall.Answer (EN)ImageA postprocessor and a preprocessor solve different tasks and work at different stages of CSS processing. --- ### **1. When it works** | Tool | When it is applied | |---|---| | **Preprocessor (SASS/LESS)** | *before* CSS exists: the code does not exist yet, it is only being generated | | **Postprocessor** | *after* CSS exists: processing is applied to existing CSS | --- ### **2. Main goal** | Tool | What it is for | |---|---| | **Preprocessor** | adding new capabilities (variables, nesting, mixins, functions) and simplifying writing styles | | **Postprocessor** | improving finished CSS for production (cross-browser support, minification, optimization) | --- ### **3. Type of changes** | Tool | What it does | |---|---| | **Preprocessor** | generates CSS based on extended syntax | | **Postprocessor** | modifies CSS that already exists, but **does not extend the language** | --- ### **4. Typical tasks** **Preprocessor:** - variables, nesting, mixins, functions - a modular style structure - reduced duplication - development convenience **Postprocessor:** - adding vendor prefixes (for example, `-webkit-`) - minification - optimizing the final file - supporting new CSS features before browsers adopt them (via plugins) --- ### **5. Examples** | Type | Tools | |---|---| | **Preprocessor** | Sass, LESS, Stylus | | **Postprocessor** | PostCSS with plugins (Autoprefixer, cssnano) | --- ### **Summary** A preprocessor is about **comfort and convenience when writing code**. A postprocessor is about **the quality of the finished CSS in production**. They are often used **together**: SASS first generates the CSS, then PostCSS improves it before publishing.For the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.