In WordPress, a slug is the editable part of the URL of a page that appears after the domain name. It is the user-friendly version of a post or pages title and helps to identify a page on a website in a user-friendly way. Slugs should be short, descriptive, and relevant to the content they represent. Slugs play an important role in search engine optimization and usability, so they are definitely something you want to consider.

Slugs can be edited in WordPress when writing or editing a post or page. They can also be set for categories, tags, and authors. When optimizing a slug, it is recommended to replace spaces with dashes and use only lowercase letters.

In summary, a slug in WordPress is a customizable part of a URL that helps direct visitors and search engines to understand the content better.