I know some of you want to change the default WordPress slug in category and tag as permalink in category post is concern. The default WordPress CATEGORY permalink looks like this htttp://www.your-site.com/category/wordpress
So you may want to change that to be unique or search engine URL issue.
In the latest WordPress Version, you don’t need a plugin or to hard code it in order to solve this issue, it already has a built in feature to conform your goal.
In your Dashboard, just go follow
> Settings > Permalinks
Look under the bottom of the page and you can see similar fields below.