YunoHost allows you to manage and serve several domains on the same server. For instance, you can host a blog and Nextcloud on a first domain `yolo.com`, and a web mail client on a second domain `swag.nohost.me`. Each domain is automatically configured to handle web services, mail services and XMPP services.
Domains can be managed in the 'Domain' section of the webadmin, or through the `yunohost domain` category of the command line. Each time you add a domain, it is expected that you bought it (or own it) on a domain registrar, so you can manage the [DNS configuration](dns). The exception is the domains `.nohost.me`, `.noho.st` and `ynh.fr` which are free and can be directly integrated with YunoHost.
The domain chosen during the postinstall is defined as the main domain of the server : this is where the SSO and the web admin interface will be available. The main domain can later be changed through the web admin in Domains > (the domain) > Set default, or with the command line `yunohost tools maindomain`.
Finally, take note that, in the context of YunoHost, there is no hierarchy between the domains it knows. In the previous example, you may add a third domain `foo.yolo.com` - but it would be considered as a domain independent of `yolo.com`.
DNS (Domain Name System) is a system that allows computers from around the world to translate human-readable domain names (such as `yolo.com`) to machine-understandable adresses called IP addresses (such as `11.22.33.44`). For this translation (and other features) to work, you must carefully configure DNS records.
YunoHost can generate a recommended DNS configuration for each domain, including elements needed for mail and XMPP. The recommended DNS configuration is available in the webadmin via Domain > (the domain) > DNS configuration, or with the command `yunohost domain dns-conf the.domain.tld`.
Another important aspect of domain configuration is the SSL/HTTPS certificate. YunoHost is integrated with Let's Encrypt, so once your server is correctly reachable from anybody on the internet through the domain name, the administrator can request a Let's Encrypt certificate. See the documentation about [certificates](certificates) for more information.
In the context of YunoHost, it is quite common to have a single (or a few) domains on which several apps are installed in "subpaths", so that you end up with something like this:
Alternatively, you may choose to install each (or some) apps on a dedicated domain. This might look prettier for end users, but is generally considered more complicated and less efficient in the context of YunoHost, since you need to add a new domain each time. Nevertheless, some apps might need an entire domain dedicated to them, for technical reasons.
