The core of your site will be an HTML template that follows web standards. This template will allow you to post and edit your content using a visual editor. This makes it completely customizable in its design.
Your content will get generated as static HTML so it's portable and you are able to put it on any host of your choice (or even download it to view on your computer). This also makes your site very fast.
And it's connected to Indie Aisle services to handle dynamic functionality like order processing. You'll have a dashboard you can use to manage this functionality. And you'll have access to the source code that you can host yourself, or modify.
All this combined makes up a powerful, flexible, portable, open source format that you have full control over. With an interface and guides that make it all easy to setup and use.