What is a Slug?
A slug refers to the part of a URL that identifies a particular page on your website. It typically comes after the domain name and is often referred to as the "URL extension".
A well-crafted slug can improve the chances of your page ranking higher in search engine results because it provides search engines with additional information about the content of your page.
A good slug should be concise, and descriptive, and include relevant keywords to help search engines understand what the page is about.
Why is it called a slug?
The term "slug" for a URL extension is thought to have originated from the printing industry, where a slug was a strip of metal inserted into a line of text to add spacing between words or letters.
In the context of URLs, a slug is similar to a printing slug that adds information to a line of text (the URL) to improve its readability and convey more information about the content of the page.
The term "slug" has become a standard term in the world of web development and SEO to refer to the part of the URL that identifies a specific page or a post on a website.
While the origin of the term is not entirely clear, it is likely that it was adopted due to its similarity to the printing industry term and its ability to convey a similar purpose in the digital realm.
Example of slug
Let's say you have a blog post about "29 Simple and Free SEO Tools". A good slug for that page might be:
/free-seo-tools
Another example can be:
https://seodebate.com/what-is-slug
Here the highlighted part is the “slug”.
This slug is concise, descriptive, and includes relevant keywords. It helps search engines understand what the page is about and makes it easier for users to identify the content of the page before clicking on it.
Difference between slug and permalink
Slug and permalink are related terms that are often used interchangeably, but they have slightly different meanings in the context of a website's URL structure.
A slug is part of the URL that comes after the domain name and identifies a specific page or post on a website. It typically includes relevant keywords and is designed to be short, descriptive, and easy to read.
For example, in the URL https://seodebate.com/what-is-slug, "what-is-slug" is the slug.
A permalink, on the other hand, is the entire URL that links to a specific page or a post on a website. It includes the domain name, any subdirectories, and the slug.
For example, in the URL https://seodebate.com/2022/01/01/what-is-slug, "2022/01/01" represents the date-based subdirectory, and "what-is-slug" is the slug, and the complete URL is a permalink.
Why are URL slugs important for SEO?
URL slugs are important for SEO because they provide search engines with additional information about the content of a web page.
These are important for several reasons:
They are more user-friendly: A well-crafted URL slug can make it easier for users to understand what the page is about before clicking on it. Users are more likely to click on a link with a clear and descriptive URL slug than one with a generic or confusing one.
They help search engines understand the content: Search engines use URL slugs to determine the relevance and content of a page. A concise and descriptive URL slug that includes relevant keywords can help search engines understand the topic of the page and shows it higher in SERPs for relevant queries.
They can increase click-through rates: When a user sees a URL slug that matches their search query, they are more likely to click on it. This can lead to higher click-through rates and ultimately, more traffic to the website.
They are easier to share: Short, descriptive URL slugs are easier to share on social media and other platforms, making it more likely for users to share and link to the page.
A well-crafted URL slug can improve the user experience, help search engines understand the content, increase click-through rates, and make it easier to share the page.
All of these factors can ultimately lead to higher rankings and more traffic for a website.
Is it a ranking factor?
URL slug itself is not a direct ranking factor in search engine algorithms. However, a well-optimized URL slug can indirectly impact a website's search engine rankings.
URL slugs that are concise, descriptive, and keyword-rich can improve the user experience and make it easier for search engines to understand the content of the page.
This can lead to higher click-through rates from search engine results pages and increased user engagement, which are both positive signals to search engines.
In another instance, he also stated:

So, the focus should be on creating user-friendly URLs, and changing URLs on an established website should be avoided unless absolutely necessary.
SEO best practices for URL slugs
Here are some best practices for optimizing URL slugs for SEO:
Be concise
Keep the URL slug as short and simple as possible while still accurately describing the content of the page. Avoid using long, convoluted slugs that are difficult to read or remember.

Use hyphens
Use hyphens to separate words in the URL slug, as opposed to underscores or spaces. Hyphens make it easier for search engines to understand the content of the page and improve readability.

Keep them short
While Google Chrome and most modern browsers permit URLs to be up to 2048 characters in length, it's not necessary to utilize the entire limit. It's recommended to keep URL slugs concise and catchy, using only 3-5 words.
Here is an example:
Original URL: https://www.yourwebsite.com/articles/how-to-keep-your-url-slug-short
Recommended URL slug: https://www.yourwebsite.com/articles/keep-url-slug-short
Include relevant keywords
Include relevant keywords in the URL slug that accurately reflect the content of your web pages. This can help search engines understand the topic of the page and improve its relevance in search results.

Avoid special characters
Avoid using special characters, symbols, or punctuation marks in the URL slug as they can cause issues with URL encoding and may make it more difficult for search engines to understand the content of the page.
Be consistent
Keep your URL slugs consistent across your website to improve navigation and user experience. Use a clear and logical structure that makes it easy for users to navigate your website.
Avoid changing the URL slug
Once a URL slug has been published and indexed by search engines, it's best to avoid changing it as this can cause broken links and negatively impact SEO. If you must change the URL slug, set up a 301 redirect to the new URL.
By following these best practices, you can create URL slugs that are optimized for SEO and improve the visibility and relevance of your website in search engine results.
How to optimize your slug in WordPress?
Optimizing your slug in WordPress involves creating a concise and descriptive URL for your post or page that includes relevant keywords.
Here are the steps to optimize your slug:
Go to your WordPress dashboard and create a new post or page or edit an existing one.
Look for the field or section where you can edit the permalink or URL slug.
Remove any unnecessary words or characters from the slug, such as dates or special characters.
Use hyphens (-) to separate words in the slug.
Include relevant keywords in the slug that accurately reflect the content of the page.
Keep the slug concise and avoid using long phrases or sentences.
Click the "Save" or "Update" button to save your changes.
Caution: It is important to note that changing the slug of an existing post or page can affect its search engine rankings and result in broken links if the old URL is no longer accessible. To avoid this, you can set up a 301 redirect from the old URL to the new URL.
Takeaway
URL slugs are an important part of SEO as they can impact search engine rankings and improve user experience.
A well-crafted URL slug should be concise, descriptive, and include relevant keywords. In most CMSs, the URL slug is automatically generated based on the title of the post or page, but it can be edited to improve SEO.
When changing the URL slug of a page or post, it's important to set up a 301 redirect from the old URL to the new URL to avoid broken links.