What's an account ID, and how can I find it?

Account ID is a unique number that helps identify you among other players. 

Note
If you have several characters (game profiles) on different servers, each of them will have its unique account ID.

To find your account ID, tap your avatar in the upper-left corner of the main game screen:

Here you will see the information about your character, including your account ID:

Press the button next to the ID to copy it.