u/Useful_Cake_5901

Hello! I am new to quantum mechanics and stuff, and I am just starting to learn about superposition. I am a bit confused about it and would like some clarification on this: is superposition saying that a system does exist in multiple states simultaneously (like with 100% certainty), or that it has a probability of existing in multiple states simultaneously? For example, does a coin exist in a state of being both heads and tails (both 100%), or exist in a state of having a 40% probability of being heads and a 60% probability of being tails?

Along with this, I am confused about how the results of the double-slit experiment prove superposition.

Would really like some clarification on this if anyone can help!