Now, oligosaccharides are basically very small polysaccharides that can have anywhere from three monosaccharides to, let's say, twelve monosaccharides. Now, oligosaccharides can be attached onto proteins and we attach them onto proteins via specific amino acids. So there are only three different amino acids that we can actually modify by covalently attaching these sugar molecules. And this includes asparagine, amino acids, serine, amino acids, and three an amino acids. And out of these three types of attachments, we only have two types of bonds that can actually form. We can have the N glycocitic bond that can form between the sparring and the sugar, or we can have the O glycocitic bond that can form between the oxygen on the serine or thorianine and that corresponding sugar molecule.