A slug is the URL-friendly part of a web address. For example, in "skuwrj.com/articles/my-great-article", the slug is "my-great-article".
Why Should You Care?
If you're writing anything for the web, slugs matter. They should be descriptive, lowercase, and use hyphens instead of spaces. A good slug generator does all this automatically!
SEO people care a lot about slugs. Clean, keyword-rich slugs can actually help your search rankings. Who knew?