A new Site app begins with its first post, so it looks like a site from the start
A web app created with the Site starter now has one published post the moment it exists: Hello, and how this site works, at /blog/hello, with a cover. The front page leads with it, the blog lists it, and its page is a short tour of the starter with the code it runs on: the post model and its publish action, how pages read records in server code, how the contact and newsletter forms become records and email, the CLI, the tests, and where to take the site next. It's an ordinary post record, written as the app is created rather than kept in a file: edit it or delete it in Records → post.
Before this, a new site opened on its empty states, since everything that makes the pages read as a publication is post content. Apps created earlier aren't changed; the post's text is in the Apps package, for anyone who wants to add it by hand.
A post whose cover is an SVG, as this one's is, keeps the site's own card for link previews instead of the cover.
More in The starter files.