First things first, I had no idea where to post this. I am sincerely sorry if a moderator had to move this!!! 
I have seen people say having a “theme” for your application helps (being focused on one thing).
“In order to get the attention of admissions when you apply, it would be helpful if your essays reflect a particular interest that you have pursued on your own. If this interest relates directly to your planned college major, all the better. NHS and Key Club are nice because joining them shows sociability and interest in doing service. But having a particular interest (a sort of theme for your application) might be even more important.” - @BunnyBlue
This interested me, and I want to know more. Could someone explain in depth about what this means???