Any of a group of polymers found in cell walls and cell membranes of certain gram-positive^* bacteria. Teichoic acids are a chain of linked sugar alcohol residues. The sugar alcohol residues are linked together by their phosphate component. To this base, various sugars (ribitol, glycerol) and amino acids can be additionally added, giving even more diversity. The diversity of teichoic acids is important because this helps to differentiate the bacteria that synthesize them. Additionally, these differences are important for the immune system to be able to recognize different species of bacteria through their teichoic acids, because some teichoic acids function as antigens for bacteria. Antigens stimulate the immune system to make antibodies against a particular foreign entity.