Basically, yes. They happen when someone gets overwhelmed by bright lights, loud noises, etc., and just don’t have enough energy to “deal with it,” so to speak. I’d send a link from this really good site I found a while back, but I don’t know yet if links are an okay thing to put in the comments.
T6J2E5 and NLTLF are wrong about meltdowns. As an autistic person, I can say with certainty that meltdowns are indeed opposite from tantrums. Good on Rainbow Dash and Fluttershy for helping Pinkie through this challenging moment.
So meltdowns are when you are unable to do anything?
Edited
Or, you know, just accept that everyone needs a ing hand sometimes.
True but Sometimes understanding why it happens is Important
Its not like crying quietly is very much possible