When you publish a page or post, WordPress creates a unique URL address for that article. The default format of the URL can be modified to improve human readability and possibly improve search engine ranking.

Go to Settings -> Permalinks and under common settings select either “Post name” or “Custom Structure”. If you select Custom Structure then enter “/%category%/%postname%/” (without quotes) in the fillable field.

Save the changes and you are on your way.