Roadmap
A roadmap lays out what you'll work on next, and roughly when. Once your site launches, the wish list never stops growing with new features, content updates, fixes, and experiments. A roadmap takes that pile and turns it into a sequence, so you're making deliberate choices instead of reacting to whoever shouts loudest.
It's a living document, rather than a contract; priorities shift as you learn from your web analytics and hear from your audience, and a good roadmap shifts with them. The product owner typically keeps it current and decides what rises to the top.