2 x 500 Ecency points reward #2

This one will be easy, I bet ...

What is this and what is it used for? Exactly correct answers only, please. The first to answer correctly receives 500 Hive account@ecency points.

Yes, you can check the web page but I guess you won't need it.

Oh, the one that explains (well enough) the personal WHY gets 500 Hive account@ecency points too.

better and better
:ervin :lemark