What does case sensitive mean?

A system that is not case-preserving is necessarily case-insensitive, but it is possible and common for a system to be both case-insensitive and case-preserving. This combination is often considered most natural for computer uses, because most people prefer using the correct capitalization but will still recognize others. For example, if someone refers to the "uNiTeD states oF AMERICA", it is understood to mean the United States of America, even though the common capitalization looks better.