"Checking Your Types: An Overview of Ruby's Type System" was the first conference talk I've ever given, which was prerecorded and premiered at Ruby Day Italy 2021. Below are the slides and some external links to tools and references that were a part of writing the talk.
My talk focused on the new features in Ruby 3, and mentioned the type checkers linked below. The example code was checked using Steep.
Below is a list of bookmarks to works that I referenced as a part of learning about type systems, Ruby and Ruby's type tools. I hope that it provides a good starting point for any deeper reading you'd like to do into the topics my talk mentioned!