One of my students asked about a post they found on an English Language stack exchange. I poked around, and there’s some good stuff here: English.StackExchange.com.
Like many message boards, it’s crowd-sourced and imperfect. However, some of the explanations here are more practical and to-the-point than all that infotainment on social media. Plus it’s a back-and-forth, so it reads more like a conversation. Good stuff.