iTerm2 is well known as one of the most powerful, high-quality pieces of software available on the Mac, and deservedly so. It's packed to the gills with features and settings that feel like they could take a lifetime to learn. Here are a few I've picked up over the years that have found their way into my daily usage.
When I first started using Emacs I thought it was pretty weird. I had questions like Why are windows called frames, and tabs called windows? and What the hell does `C-x C-s` mean?.