The overall site design is the set of rules and actions that are executed once a site has been provisioned. Site designs give you the ability to add lists with various content types and columns, configure logos and themes, and join to hub sites.

A site design can have one or more scripts associated with it (which perform the actual actions).

Site designs and site design scripts are not linked in any way to sites – the actions that are defined are only run once. If you change the site design or site scripts, modern sites that you have configured don't get retroactively updated with the changes. If you want your new changes to be applied to the site design, you'll need to run them on the sites you want to be updated.

Next, we'll look at creating a basic site design using a site design script.