What does this mean in layman's terms?
Okay, so Apache is what distributes content. When you talk to Apache, it figures out what to do based on the request.
https://kiwifarms.net/
This tells apache a lot. So does the hidden stuff in your request headers, stuff you send to every page. unwittingly. That URL alone tells people you want kiwifarms.net, and you're using the SSL HTTP protocol. So, it should send you content and it should encrypt it.
Normally, Apache will send you the contents of a file. If you request a directory, it will list the contents of a directory. Apache is configured to open index.php/html automatically, if you request a directory and that index file exists.
PHP is the language our website runs on. Apache is configured using mod_php5 to figure out how to open .php files, so that when you ask for index.php by opening kiwifarms.net, you get something way different than the raw text. In fact, index.php handles everything. When you access this URL, it opens it as the 2nd URL.
/threads/technical-grievances-thread.6828/#post-473755
index.php?/threads/technical-grievances-thread.6828/#post-473755
Literally every request made to XenForo is handled by that one file. It works in harmony with a complicated Apache system to make requests simple and easily understood for the end user.
mpm_event is a way to tell Apache how to handle requests. It uses what's called threads. Threads are relatively new technology and are incompatible with PHP, the scripts that run the website. Instead of tying to queue up every request individually, it attempts to split the request up into multiple threads. This works much faster. However, by enabling it, it
disabled all the complicated bits that made that request work. After enabling it, instead of getting the content rendered by index.php, you simply got index.php's raw code.
