system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: PTSD, Post Traumatic Stress Disorder

I just need to know what this actually signifies. I see the wiki page for it and things and know what triggers it but I just need to know what it is I guess. My mind can't seem to process it for some reason lol. I know there's treatment but is there a permanent solution other than medication? And how exactly does sertraline (zoloft) work?
gpt
When you were little you used to get Mrs Fields cookies whenever you visited your Grandpa. There wasn't a Mrs Fields in your neighborhood, so it was a feature of every trip you would take to visit them. After a while you move out on your own, you don't visit as much, and when you do, you don't go out for cookies. Except one day, you're out with your own kids and you pass a Mrs Fields cookie shop. For five or ten seconds, you're five, not thirty-five, and you're holding your Grandpa's hand while waiting for a delicious slab of gooey chocolaty cookie. The memory is almost completely overpowering and you have to sit down for a minute. Meanwhile, your kids are wondering why their Mom is zoning out in front of a little mall kiosk.

Now, replace getting a yummy cookie with the worst thing that ever happened to you in your life. Maybe when you went there something horrible happened. Instead of happiness and fuzzy fluffy memories with your Grandparents, you think of how scared and alone and in pain you felt. You think of people who can't think any more. You think of not being able to run away, and you think of how helpless you were. And you might even think about the horrible things you did to get out of that situation.

That's PTSD.