XenForo is a powerful and feature-rich open source forum software solution. It is designed to be fast, reliable, and easy to use. It provides a user-friendly interface for users to easily navigate and interact. It features an advanced permission system, custom user profiles, customizable user groups, private messaging, and much more. XenForo also has a built-in search engine, which allows users to quickly find content related to their interests. XenForo also has an expansive theme system, allowing users to customize the look and feel of their forum. Its powerful API enables developers to customize and extend the functionality of their forum. XenForo is an ideal solution for creating an engaging and vibrant community.
Because it's great, and does what I need it to do. Better then XenForo