Why slugs matter more than they look
The slug is the human-readable tail of a URL, and it does three jobs at once. It tells a person what a page is about before they click, it gives search engines a keyword signal, and it survives being copied into messages and documents without turning into unreadable percent-encoded noise.
Google has recommended simple, descriptive words separated by hyphens for well over a decade. The alternative — /page?id=4821 — tells nobody anything, and when shared it looks like something you shouldn't click.
Hyphens, not underscores
This one has a definitive answer. Google treats a hyphen as a word separator and an underscore as a word joiner. That means css-animations is read as two words, while css_animations is read as the single token "cssanimations" — which nobody searches for.
Also keep slugs lowercase. Web servers on Linux treat URLs as case-sensitive, so /My-Page and /my-page can resolve to different pages — or one of them to a 404 — creating duplicate content or broken links depending on which version gets shared.
Removing stop words — and when not to
Words like "the", "and", "of" and "for" carry little search value, so removing them makes slugs shorter and more keyword-dense. /10-best-css-tricks-beginners-2026-guide reads better than the full headline and loses nothing.
But don't strip blindly. Occasionally a stop word is load-bearing — removing "not" reverses a meaning, and phrases like "The Who" or "Fear of the Dark" break entirely. Read the result before publishing; this tool also keeps the original words if removing them would leave the slug empty.
Never change a published slug
Once a URL is live, it accumulates value: backlinks pointing at it, social shares, bookmarks, and its own ranking history. Change the slug and all of it points to a 404 — you lose the link equity and the visitors at the same time.
If you genuinely must change one, set up a 301 redirect from the old URL to the new one. That passes the accumulated authority across and keeps existing links working. Treat it as a last resort rather than routine tidying, and take a moment to get the slug right before publishing instead.
A few practical limits: keep slugs reasonably short (three to six meaningful words is a good target), strip accents to their ASCII equivalents so the URL doesn't get percent-encoded, and drop dates unless the content is genuinely time-bound — /2024-guide looks stale the moment the year turns.