At its simplest, a Substack publication is an email newsletter that you can charge money for. You write it, readers pay you, and everyone goes away happy. As well as the newsletter, however, you get a free website, hosted by Substack at a subdomain of your choosing. Example: you.substack.com. Everything you send to your subscribers also gets published on your website. You can also choose to publish articles to your website that don’t go out by email.