Gugol is number 1 followed by 100 zeros.
This name came about when, on one occasion, American mathematician Edward Kasner asked his 9-year-old nephew Milton Sirotta what number there was. The boy's response (something like guuugol) was not very encouraging, but in Kasner's mind it was a nice joke.
In honor of his nephew, he called gugol ("googol") the number 1 followed by 100 zeros or, to put it another way, the number 10 raised to 100.
He then used gugol as a basis for naming an even larger number: the gugolplex, which is equivalent to "10 raised to 1 gugol". Imagine how many sheets of paper it would take to write the gugolplex number in full…