Also if your host and client devices both support mDNS / Bonjour, you don’t even need to type the IP address.
For example if your Ubuntu Linux desktop machine has host name foobar, and you run a http server on for example port 8000 then you can use your iPhone and other mDNS / Bonjour capable things to open
And likewise say you have a macOS laptop with hostname “amogus” and for example http server is listening on port 8081, you can navigate on other mDNS / Bonjour capable devices and machines to
For example if your Ubuntu Linux desktop machine has host name foobar, and you run a http server on for example port 8000 then you can use your iPhone and other mDNS / Bonjour capable things to open
http://foobar.local:8000/
And likewise say you have a macOS laptop with hostname “amogus” and for example http server is listening on port 8081, you can navigate on other mDNS / Bonjour capable devices and machines to
http://amogus.local:8081/