Google’s official position is straightforward: hyphens are treated as word separators, while underscores are treated as word joiners. In practical terms, best-seo-tools is understood as “best seo tools,” but best_seo_tools may be read as “bestseotools” as if it’s one combined word. That’s why hyphens are considered more SEO-friendly—they make it easier for Google to parse a URL into meaningful words. Even though modern search engines have improved and can often interpret both formats, Google still recommends hyphens because they improve readability, provide clearer keyword separation, and reduce ambiguity that underscores can sometimes create.

If you want your URLs to perform well in 2025, the best approach is to keep them short, descriptive, and easy to read, while using hyphens as your default separator. Avoid unnecessary numbers, extra words, or messy parameters, stick to lowercase letters, and don’t change old URLs unless it’s absolutely necessary—if you do, use proper redirects. A simple comparison makes the point clear: www.example.com/mens-suits-charcoal-grey is more readable and keyword-friendly than www.example.com/mens_suits_charcoal_grey. Both can rank, but the hyphen version is typically clearer for users and search engines, which can help improve CTR and overall SEO performance.