This button makes your art pieces interactive, as long as you're on your home WiFi network. If you want to take it out and show it off to the world, the easiest way to stay connected is to use a proprietary WiFi router. This will allow you to set up your own local WiFi network. It doesn't need internet connectivity, so you don't need to hook it up to an internet account or Ethernet cable -- just power the router up and you'll get a LAN (local network) which all your WLED instances can use to communicate with each other.

Each WLED instance has WiFi credentials set up in the WiFi Setup screen. To make my life easy, I gave my portable router the same WiFi name and password as my home network. This way I don't need to change WiFi credentials when I'm away from home -- my projects will simply work whether I'm home or away. It does make it difficult to test the router setup from my house -- having two of the same network names creates a conflict -- but in the long run I'm glad I did it this way.

Each company has a different WiFi setup software package, so read the directions that come with your router. All you need to do is set up the network name and password, and then make the WiFi settings on your WLED instances match. 

Now you can take your projects anywhere, and sync them together or control them from your phone without needing to be within internet range.