A googol is the number 10 raised to the 100th power, or 
. To give an idea of the size of this number, it is greater than the estimate of the total number of molecules in the universe.
A googolplex is the number 10 raised to the googolth power, or 
.
Neither of these numbers have any practical application and are just given as an example of exponentials and numberplexes.
The name was created by American mathematician Edward Kasner's nephew Milton Sirotta.
The search engine Google's name is derived from googol.