ELI5 Balloons - why is there a ring at the opening of a balloon?

Why is there a ring at the end of the opening of a balloon? What creates the noise of a ballon popping? Who invented the ballon? Why do helium balloons shrink in size over time? .. we explain like I'm five Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: marv1nnn, trooper_x, secretantworshiper, fujikitakyusho, brian_vogel, 18_usc_47 and moskau50 To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter: https://www.twitter.com/eli5ThePodcast/ or send us an e-mail: [email protected]