When creating an article, you can decide whether to make it public, for subscribers only, or split.
Public posts can be visited by anyone on the internet. These posts are great, if you just want to get awareness for your content. (You will still earn money for subscribers visiting your public posts.)
These posts are great if you want to write exclusively for Coil subscribers. Only the title will be visible for users without a Coil subscription.
Split posts combine the best of both worlds. They have a public part and a subscriber-only part which makes them ideal to share with potential Coil subscribers to grow your paying audience.
Note: To create a split post you start off with a public post. Once you have written your public part you can add a lock divider from the + menu. Everything added below that lock divider shows up to Coil subscribers only.