Poi's discovering
I’m not sure what you mean. Each zone in the game has a set number of points of interest. You have to discover them by character, not by account. Once you’ve discovered a poi, you can mouse over it on your map to see what it is called, as well as link it in chat to others. You can only discover them by running onto them (or very near them as in the Whispers secret chamber, or vertically straight over them if you are above a cavern holding them though sometimes you must find your way to the same altitude to get the credit).
The main game mechanic reason to discover them is for xp, and if you want 100% world completion you will need all the pois in all the zones as part of that achievement.