SharePoint Online HubSite is a building block for your intranet. It allows you to bring together related sites and create cohesion between those sites. You first register a site to be a HubSite, then associate other sites to it.
By doing this you will get :
A shared hub navigation bar on every site in the hub
Theme managed by the HubSite
Cross site content display
Search results scoped to all associated sites
From a IT prospective, using HubSite is very flexible as you can associate and revoke the association in one click. The collaboration world is a moving field, team structure are subject to change very often. This solution is tailored to provide a way to relate sites to each other without the lack of flexibility when building intranet with sub-sites.
Points to consider :
-Build your HubSite and associated sites using the Modern experience, the hub navigation will only show up on modern pages. Modernize your SharePoint Classic sites
–Registering a HubSite can only be done by a SharePoint Online administrator. However, associating a site to a HubSite can be done by any owner of the site to associate who has access to the HubSite. SharePoint administrators can filter who can associate site to a HubSite in the SharePoint Online admin center. We cover this point in the article Register a SharePoint Online Site as a HibSite
-It’s important to understand that the HubSite will be the home destination for users, so it most likely will end up being a Communication site. Although you can register a Team site as a HubSite.
-It is also the place to manage the branding aspect of the whole hub, so you might want to choose carefully the HubSite owners and communicate accordingly.
-The permission are not inherited from the Hubsite to the associated sites, each site retain its own permissions. User will only see information they have access to when sites display content from associated sites.
-When a site is associated to a HubSite, all its sub-sites will be part of the Hub. A site can be associated with only one HubSite.
-You can also leverage the Site Design feature to automatically join a new created site to a HubSite. This can greatly impact the site creation process you choose for you organisation. We cover this topic in Associate a SharePoint Online Site to a HubSite
-Last but not least, you can attach a Site Design to a HubSite so it will run to automate action on a site that is associated to this HubSite. See Microsoft documentation
If you need more information on HubSites, here is a link to the official documentation from Microsoft docs.
You might also want to read related articles where we discuss how to register a HubSite and how to associate sites to a HubSite.