Why do computers use binary

I learned that computers use a digital signal which is a system that represents digits, to send sound through headphones. I also learned that if a numbers too high it may get confused for a different one and throw off the entire system. I learned that in order to fix that you just have to give it a smaller range. I am confused about the way that works to be completely honest. I'm also confused as to why it matters how many digits are in the range. I am curious as to how this was invented.