Typically, the term "ester" refers to a carboxylate ester, but technically, the parent acid of an ester can be any acid.For example, methyl formate is a carboxylate ester.

Methyl formate, also called methyl methanoate, is the methyl ester of formic acid. The simplest example of an ester, it is a clear liquid with an ethereal odor, high vapor pressure and low surface tension.

It is liquid commonly known as methanesulfonic acid ethyl ester.

It is solid material.

It is viscous liquid having amber colour.

Sorbitan esters ( also known as Spans ) are lipophilic non ionic surfactants that are used as emulsifying agents in the preparation of emulsions, creams, and ointments for pharmaceutical and cosmetic use.