What does each entry in index management actually do?

Question

I want to have a better understanding of what each entry does and what happens when it requires a reindex.
I've read the Magento Docs fully but they aren't known for breaking down things into the most understandable pieces. I know the difference/functionality of update on save and scheduled. Just not quite sure what it is doing behind the scenes.

Specifically, I do not understand what the entries for :
Rebuild Design Config index and Rebuild customer grid index are for.
Is there a directory I can locate these files in and change them manually?

Any help will be greatly appreciated.

Yes I did. However, my question still remains unanswered.. what are the design config and customer grid index for? And where is the actually directory for these or the data found? — Daniel Barenboim, Nov 30 '16 at 18:15

score 0 · Answer 1 · answered Nov 30 '16 at 18:48

Magento use flat table customer_grid_flat for customer grid so when you rebuild index for customer grid it will take data from eav tables and put data here in flat table for customer.

I can't see design config in my setup. It seems to be available after some changes.

What does each entry in index management actually do?

1 Answers1