What is the largest finite number that you can imagine? Is it all the grains of sand on all beaches in the world? Or, is it the total number of subatomic particles in the entire observable universe? Or, the famous googol number ($10 ^{100}$) that Google was inspired by? Or even, is it a googolplex ($10 ^{10^{100}}$)?
All these are nothing but absolute zero compared to Graham's Number, which is the largest finite number that human beings can ever imagine!
