what is the easiest way to make a forum?

i know some javascript and html but that's it, i know you need to host the website somewhere by paying monthly fees depending on how much visitors and data is going around. let's take Lainchan as an example, the front end is not the most complicated but what about the back end? it appears to store the data for a long time and does not require the users to register, but how does it recognize robots? there is no CAPTCHA after all the threads inside this chan will never show up on a google search but why? and what of this message in red "Lainchan has upgraded to PHP 8.1" what does it exactly mean? tldr: what is the easiest/cheapest way to make and operate a forum style website

god dangit you're an idiot these are just publicly available programmes its in the bottom block of text you moron. my dear imbecile just look this up gosh lainchan uses a modified vichan maintained publicly on fuarrrking github you absolute peabrained idiot learn to study

Moved to >>>/q/12840.