Why Do Infinity and Infinity Not Always Add Up?

Infinity is like a never-ending cookie jar, you can always take one more cookie. But sometimes, if you have two infinite jars, they don’t just add up to one bigger jar of infinity. Imagine you have an infinite number of cookies in one jar and another infinite number in a second jar. If you pour them together, you might still only have the same amount of cookies as before, like magic! But that’s not actually magic; it's how numbers work when they’re infinitely big.