User blog comment:SteviWunda/How big is this number?/@comment-30754445-20170424203047/@comment-27516045-20170430221123

There are many places where you can learn more aout googology - there's al ink section on the wiki. I'll give you two pages to start you off, they often explain things in a way that is easy to understand:

Rob Munafo's large number pages: http://mrob.com/pub/math/largenum.html

Sbiis Saibian's One to Infinity website: https://sites.google.com/site/largenumbers/

Both of these introduce many of the notations people have mentioned on the comments.