Search function in ES

Hi,

I don't get it how ES search & ES extended search works. How should it?

As I understand ES search is using Joomla smart search component, right? That means ES search is getting strings out you put in there before by using indexing function. What is exactly indexed, just titles/descriptions? How about content from custom fields?

EA search is looking at k2 item, tag, event, category, group, photo, people, video, and article by choice. Where is ES extended search looking for data? Seems like it just lookup custom field values from the user profile types, no group custom fields, no event custom fields. Is ES extended search just for searching custom user field values?

Can you please clarify?

Thanks.