A URL slug is the human-readable part of a web address that identifies a specific page — in autonomiqtech.com/what-is-a-url-slug, the slug is what-is-a-url-slug. It seems trivial, but slugs affect click-through rates, SEO, and whether a link still works in two years. Getting them right is quick; fixing them later is painful.
Why the slug earns its keep
Three reasons. First, readability: a person deciding whether to click /best-budget-laptops-2026 versus /p?id=48213 can tell what they will get. Second, SEO: keywords in the slug are a small but real relevance signal, and descriptive slugs earn more clicks in search results. Third, sharing: a clean slug in a chat or social post is self-explaining and looks trustworthy, while a random string looks like spam.
The best-practice checklist
Keep slugs short and descriptive — three to five meaningful words beats a full sentence. Use hyphens, not underscores, because search engines treat hyphens as word separators. Stick to lowercase to avoid duplicate-URL confusion on case-sensitive servers. Drop stop words (a, the, of) when they add nothing. Include your primary keyword near the front. And leave out volatile details like the year or a category that might change, unless they are genuinely part of the page’s identity.
Things to avoid
Avoid spaces (they become ugly %20 codes), special characters, and ID-only slugs like /node/1123. Do not stuff keywords — /cheap-laptop-best-laptop-buy-laptop reads as spam to both people and Google. And avoid dates in the slug for evergreen content, because /2023-guide looks stale the moment the calendar turns.
The rule that saves you later
Here is the one that experience teaches: once a URL is published and indexed, changing its slug breaks every existing link and can cost ranking. If you truly must rename it, always add a 301 redirect from the old slug to the new one so visitors and search engines follow along. The cheapest fix is to write a good, timeless slug on day one so you never have to touch it.
What a good slug looks like in practice
The clearest test is whether someone can guess the page content from the URL alone, read it aloud over the phone, and type it back without errors. Compare these two addresses for the same article.
/blog/post.php?id=4471&cat=12 tells a reader nothing and cannot be dictated reliably. /guides/how-to-sharpen-a-chef-knife tells them everything, survives being pasted into a message, and still makes sense if the site is redesigned later.
Rules that actually matter
Use hyphens rather than underscores to separate words, because search engines have historically treated hyphens as word boundaries and underscores as joiners. Keep everything lowercase, since URLs are case-sensitive on most servers and /About and /about can resolve to different pages or to an unnecessary redirect.
Strip filler words where they add no meaning. /the-complete-guide-to-the-best-ways-of-sharpening-a-knife carries the same information as /knife-sharpening-guide while being harder to read and easier to mistype. Avoid dates unless the content is genuinely time-bound, because /2024/knife-guide looks stale the moment the year turns even if you keep the article updated.
The rule people break most often
Changing a slug after publication breaks every existing link to that page, including bookmarks, shared messages and inbound links from other sites. Search engines treat the old address as gone and the new one as unrelated, so accumulated ranking signals are lost rather than transferred.
If a change is genuinely necessary, publish a permanent redirect from the old address to the new one and keep it in place indefinitely. A 301 passes the great majority of ranking value across and keeps old links working. Deleting the old URL outright, or serving a soft 404, discards that value entirely. The cheapest version of this lesson is to spend an extra minute choosing the slug before you publish rather than fixing it afterwards.
Handling non-English characters
Accented and non-Latin characters are legal in modern URLs but get percent-encoded when copied, which turns a readable address into an unreadable string. A page titled "Café" can become /caf%C3%A9 when pasted into a chat window. Most publishers transliterate to plain ASCII for the slug, producing /cafe, which stays readable everywhere at the cost of a small loss of fidelity.
Common questions
Should I use hyphens or underscores in a URL slug?
Use hyphens. Google treats hyphens as word separators but underscores as joiners, so hyphens are better for readability and SEO.
Does the URL slug affect SEO?
Yes, modestly. A short, keyword-relevant slug is a small ranking signal and improves click-through by making the link readable and trustworthy.
Can I change a slug after publishing?
You can, but it breaks existing links and can lose ranking. If you must, add a 301 redirect from the old slug to the new one.
Should I put the year in a slug?
Avoid it for evergreen content, since it looks outdated quickly. Only include a year if the page is genuinely tied to that year.