Glyceric acid

Glyceric acid is a natural three-carbon sugar acid obtained from the oxidation of glycerol. 
CH2OH-CHOH-CH2OH+O2→CH2OH-CHOH-COOH+H2O
Salts and esters of glyceric acid are known as glycerates.
Biochemistry.
Several phosphate derivatives of glyceric acid, including 2-phosphoglyceric acid, 3-phosphoglyceric acid, 2,3-bisphosphoglyceric acid, and 1,3-bisphosphoglyceric acid, are important biochemical intermediates in glycolysis. 
3-phosphoglyceric acid is an important molecule for the biosynthesis of the amino acid serine, which in turn can be used in the synthesis of glycine and cysteine.
References.
2. J.Berg,J.L.Tymoczko,L.Stryer. Biochemistry,7th edition.