https://www.businessinsider.com/the-different-sizes-of-infinity-2013-11?r=US&IR=T
Extract
Infinity is a powerful concept. Philosophers, artists, theologians, scientists, and people from all walks of life have struggled with ideas of the infinite and the eternal throughout history.
Infinity is also an extremely important concept in mathematics. Infinity shows up almost immediately in dealing with infinitely large sets — collections of numbers that go on forever, like the natural, or counting numbers: 1, 2, 3, 4, 5, and so on.
Infinite sets are not all created equal, however. There are actually many different sizes or levels of infinity; some infinite sets are vastly larger than other infinite sets.
How my heart sings 