What is a URL Slug?

Create user-friendly and SEO-optimized URL structures

Definition of URL Slug

A URL slug is the part of the URL that comes after the domain or subfolder slash ("/"). URL parameters and hash parameters are not part of the URL slug.

Good URL slugs typically use an easy-to-read format, which helps readers and search engines better understand the page content. However, depending on the website's permalink structure, slugs can also contain numbers, dates, days of the week, author names, and other information.

Thanks to WordPress, where slugs are clearly visible and easy to edit, this term has become widely popular among website administrators and SEO practitioners.

Example: https://ahrefs.com/blog/keyword-research/#finding-keyword-ideas

In the example above, keyword-research is the URL slug.

Are URL Slugs Important for SEO?

While there are many factors that affect page rankings, the role of URL slugs as a ranking factor is overestimated in the SEO community. Many people are enthusiastic about stuffing keywords into URLs, believing this will significantly improve rankings for target keywords.

Google Search Advocate John Mueller has stated that URLs are a very lightweight ranking factor.

Here's an excerpt from John's discussion about the importance of URL slugs:

"We use words in URLs as a very, very lightweight factor. As far as I recall, this is primarily a factor we consider when we haven't accessed the content yet. So, if it's the first time we're seeing this URL and don't know how to categorize its content, then we might use words in the URL to help us rank better. But once we crawl and index the content, we get more information. At that point, whether the URL is in German, Japanese, or English basically doesn't matter."
— John Mueller, Search Advocate

Therefore, before indexing, it can sometimes help Google understand page content. However, after indexing, it becomes irrelevant because Google can obtain more information to help with rankings.

So, does this mean URL slugs are completely unimportant and there's no need to use descriptive slugs?

An informative and descriptive URL can help readers immediately understand the page content and be more likely to click on it.

For example, if you share this URL: https://ahrefs.com/blog/what-is-a-url-slug/ with your friend, where what-is-a-url-slug is a descriptive slug, it clearly tells your friend the topic of the article.

However, if the URL is like https://ahrefs.com/blog/article-123, your friend won't know what the content is about. This might make them find it unappealing or even suspicious, making them less likely to click.

Descriptive slugs are also easier to remember and even easier for others to link to.

SEO Best Practices for URL Slugs

Now that you know optimizing URL slugs to make them user-friendly is crucial, let's dive into four best practices to follow when customizing slugs.

1. Keep it Short and Informative

Although keywords in URLs won't significantly improve your rankings, including the main topic or keyword in the URL slug is still one of the best SEO practices.

It's best to keep slugs short and clear, making them easier to remember and understand, and able to summarize the title.

So, instead of using a slug like /what-is-keyword-density-and-why-is-it-important, use /keyword-density.

2. Use Hyphens Instead of Underscores to Separate Words

It's always good practice to separate words in slugs, making them easier to understand. Google recommends using hyphens to separate words in slugs, not underscores. Google recognizes hyphens as word separators, helping it understand page content.

3. Avoid Using Dates in Slugs

This mainly applies to blog posts. Suppose you wrote an article in 2022 with the slug /best-domain-providers-2022, but next year you want to update it to 2023 with more relevant data. For this, you must set up a redirect to ensure users don't end up seeing a 404 page.

Therefore, it's best to avoid using dates and set the slug to something like /best-domain-providers.

4. Use Lowercase Letters

Although most web servers treat uppercase and lowercase URLs the same way, this isn't always the case. Technically, everything in a URL after the domain is case-sensitive, so some servers treat them differently.

Since URLs are traditionally lowercase, it's recommended to use lowercase letters to simplify operations.

URL Slug Optimization Strategies

1. Keyword Optimization

Include main keywords in the slug, but keep it natural and not over-optimized:

  • Use main target keywords
  • Avoid keyword stuffing
  • Maintain natural readability
  • Consider long-tail keywords

2. User-Friendliness

Create URLs that are easy to understand and remember:

  • Use descriptive words
  • Avoid technical terms (unless necessary)
  • Keep it concise and clear
  • Easy to share and spread

3. Technical Considerations

Ensure URLs are technically correct:

  • Avoid special characters
  • Use standard ASCII characters
  • Keep URL length reasonable
  • Ensure uniqueness

Frequently Asked Questions

What's the difference between URL and slug?

A URL is the complete path containing the protocol, domain, and slug. The slug is the part after the slash in the URL, in this case /what-is-a-url-slug.

How to change URL slug format in WordPress?

To change the URL slug format, you need to modify the permalink structure in WordPress. Steps:

  • Visit "My Site"
  • Go to "Settings"
  • Click "Permalinks", then choose your preferred structure from existing options, or create your own structure.

What's the maximum length for URL slugs?

Google Chrome and most modern browsers allow URLs up to 2048 characters. But this doesn't mean you should use all characters. Stick to 3-5 striking words in your slug.

What happens if I change a page's URL slug?

Editing a URL slug changes the page's address. This means all links pointing to that page will become invalid, and users will see a 404 error.

To prevent this, you need to create a redirect from the old URL to the new URL. In WordPress, this can be easily done through redirect plugins.