Generalization Error/Bound

[noahdavis]

I'm a little bit confused by the section "Generalization error" on Page 40 of the LFD textbook. What is the purpose of establishing a "Generalization bound"? Why is the generalization bound a useful rephrasing of Hoeffding Inequality?

I'm also confused of the use of the word "tolerance" - since epsilon and delta are both used to refer to a kind of "tolerance" ...

Thanks for any clarification you can offer.