i was asked this in my interview for internship that the most important data format seen in excel .
The most important data formats are 1) Conditional Formatting and 2) Data Formatting in excel. Although there are other various types as well; such as currency, date, numbers, etc. But the most important is Conditional Formatting; the powerful visualization technique. It allows you to format various things; Background color, Border, Number formatting & Font formatting in the data assigned with certain conditions.This function is available under home tab in excel. it has already predefined rules such as highlight rules, top/bottom rules,data bars, color scales, etc. we can also add the rule from our side as well by clicking new rule.