SubPosts is a really slick plugin for creating relationships, or “links”, between post types. The plugin let’s you easily create links between post types and then connect individual items within a post type to items within another post type. It’s great for creating links between products and documentation, products and blog posts, courses and lessons, and any other kind of linking relationship you can think of.
In Barry’s own words:
With Sub Posts anyone can create custom post type relationships, without programming a single line of code!