Yes, and no.<p>Yes they can really help you organize larger projects easily. With variables, you only have to write things once. If you change your "black" from #000 to #1a1a1a, for example, that's one change instead of dozens. Nesting is another useful feature that helps you separate one page/module from another, and keep everything contained. Mixins and functions are super-useful if you find yourself re-writing the same stuff over and over. Also, the preprocesing itself is a great way to "lint" your styles (in a surface-level way). If there's a syntax error, the preprocessor will just fail, exposing an issue that might have gone unnoticed if you were using plain css.<p>But no, they don't help you write the most efficient CSS. So if performance is your goal, you can probably write better/faster CSS if you target each element manually, rather than letting the preprocessor target based on your nesting.<p>And no, they don't help you alleviate cross-browser issues; that's what auto-prefixers and shims are for. Those are different tools, also useful.<p>And no, they don't help you keep your css tiny, that's what a concatenators, minifiers, and utilities like "UnCss" are for. Also great tools, but separate ones.<p>If you want to get all the benefits you can, your CSS build tool will need to include many different phases. Preprocessing is only one phase; but may be an important one, depending on what you're looking for.<p>Also,if you want to get started, just rename your .css to .less or .scss instead, and preprocess it. Both less and scss are supersets of css, (so all valid css is also valid less and scss). You can write vanilla css inside a less file with no issues. That way, if the urge strikes you to experiment with the features of the preprocessor, you can do so immediately.