A butterfly effect is the phenomeon that a small change in initial conditions that leads to a significantly different result than if the initial conditions haven’t been changed. Have you personally witnessed such phenomeon?
Example: Your pet seeks attention and you decided to spend a few seconds to pet your pet before leaving for work/a party/shopping for grocerries/etc. You drive to an intersection and the light turns red just a few seconds before you arrive, the car ahead of you passed the intersection sucessfully. When you eventually arrive at the next intersection, you find the car ahead of you was hit on the side by another car from the intersecting road. The driver in the car ahead of you was instantly killed.
You’ve just been saved by your pet.
I decided to come home during summer break during my senior year of college. I wasn’t going to but I decided I should do something besides sitting around playing video games. I got in the car, drove for 4 hours, and got a call from my best friend that he was having some people over that night. I almost didn’t go because I was tired from the drive. I decided to go. I knew everyone there, including a girl I had been friends with for years but hadn’t seen in awhile. We were all hanging out, me and this girl ended up hooking up that night. We’ve been together over 12 years, married for 6. If I had decided to stay at my apartment and play Skyrim instead of driving home, we very likely wouldn’t be together. I think about it more than I should lol.