The essential functionality of the 'Posts 2 Posts' WordPress plugin revolves around enabling the creation of many-to-many connections among posts. What does that mean? Well, a typical WordPress website is designed to handle one-way relationships — for instance, assigning posts to categories. However, there might be instances where you need two-way or many-to-many relationships. Imagine a scenario where you have a movie review blog, and you want to connect a particular movie review post to multiple actors, and each actor, in turn, is connected to several reviews of different movies they starred. This is where ‘Posts 2 Posts’ comes in as an invaluable help.

The plugin allows you to manually create connections through a drag and drop interface. You can then display these connections in any template using a simple API, and the plugin also provides shortcodes to ensure that even users with little to no coding knowledge can conveniently apply these connections.

Another exciting feature of Posts 2 Posts is its high degree of customizability and flexibility. When defining connections between different post types, you can incorporate additional fields, specify how many items can be connected, or decide whether connections should be sortable or not. You can associate multiple post types with each other, associate posts to pages, or even connect posts to other posts. In other words, the diversity of relationships you can create with Posts 2 Posts is virtually limitless.

Moreover, this plugin was designed with performance in mind. Because it uses a single table to store all connections, it ensures that your database remains clean and efficient. It also employs a smart caching algorithm to eliminate redundant database queries, ensuring that the plugin remains lightweight and does not slow down your website.