A salt or ester of phosphoric acid. While commonly associated with fertilisers, they are involved in many biochemical processes, often as part of complex molecules, such as adenosine triphosphate. An ester is a compound formed by the reaction of an acid with an alcohol and also includes the fats and oils that are esters of fatty of glycerol.
See Adenosine triphosphate (ATP), Electrolyte, Nucleotide, Phospholipids