Here’s a link to the forum trust level guide. Trust Levels and How To Advance
Thankfully it’s a subset of Discourse’s more extensive implementation of trust: Understanding Discourse Trust Levels
Discourse is the forum software that this forum is running. It’s pretty good, IMHO. The exact requirements to reach a trust level can be customized by the moderators of a particular forum so the Discourse blog is not necessarily quantitatively or qualitatively exactly what’s going on here (and I’m just a relatively ignorant user, too-nothing to do with forum moderation!).