I have been using this beginner's tutorial (https://developer.android.com/training/basics/firstapp/creating-project) on Android application development to help me create my first Android application.
For the "Configure your project" window, the tutorial suggests using "com.example.myfirstapp" as a package name. (Obviously, my real app would not be called "myfirstapp": this is just an example.)
However, I already own a website with a subdomain and a domain other than ".com". I was actually hoping to use a website with a URL like "https://myfirstapp.github.io/" (GitHub Pages).
For my Android application, should I name the package: "io.github.myfirstapp"? Or should it be "io.github.myfirstapp.myfirstapp" since the first "myfirstapp" is part of the website name? Or should it not be that at all, since I don't own "GitHub"... I'm a little confused.
According to the comments posted above, it is okay to use a domain other than ".com" in the package name. ".io" and ".org" work as well. However, try to avoid using copyrighted or trademarked names to avoid any legal consequences.