Co-Authors Plus is a WordPress plugin that allows multiple authors to be associated with a post. This powerful tool is essential for websites with content created collaboratively by a team. It extends the capabilities of WordPress to permit more than one author to be assigned to posts, pages, and custom post types via a search-as-you-type input box.
Usage
Simply go to your posts and select any post to which you want to add an additional author, then click Quick Edit. There, you will find a new field named Authors. Using this field, you can add additional authors to the post:
As soon as a post has more than one author, its layout will automatically adjust to accommodate this: