Slug is a special version of post's name that is user-friendly and URL valid. It's used for permalinks structure in WordPress. For example, if post name is "Lorem ipsum dolor sit amet", our default slug is "lorem-ipsum-dolor-sit-amet". Since a friendly URLs structure, length and used words play the significant role in search engine optimization I suggest learning what is a slug in WordPress - it will take just 3 minutes to get it :) 

It's very similar to alias in other CMS like, for example, Joomla CMS.

Permalinks structure in WordPress

If we want to use slugs in our blog structure we need to properly configure them. Go to Settings -> Permalinks and select one of the structures that use slug and then click Save changes.

Modify post slug in WordPress

You can, of course, modify WordPress post slug if you feel for example that is too long or you think that it would be better for SEO - since it's important to keep keywords in the slug. Then edit the desired post and click Edit button visible next to slug name or in other words at the end of post permalink line.

Now you can edit slug. Click OK when you are done.

I would not recommend changing post slug after it was published. If we do that the same content will be published on multiple pages for some time. Also if you have linked your post somewhere, this link will be broken.

WordPress slug for categories and tags

You can also change slug for categories and tags.

Don't be afraid to use slugs and change them if needed. WordPress provides this super tool to use it :-)