The individual mono saccharides utilized their terminal hydroxyl group to form a O-glycosidic linkage to form di-saccharides with the loss of water (Figure 36.3). With the addition of water, it can be hydrolyzed to form individual monosaccharides. Different monomer can participate to give different disaccharide sugar.
Condensation of different monosaccharides or disaccharides give rise to polysaccharides. Polysaccharides are the storage form of the sugar and it gets hydrolyzed to give monosaccharides to participate into the metabolism to produce reducing equivalent to provide energy via electron transport system.
As the anomerc carbon participate in the formation of glycosidic bonds, it has lost its ability to form linear form of sugar, as a result it becomes non-reducing sugar. In the disaccharides or polysaccharides, terminal sugar has free anomeric carbon and called as reducing end.   

Figure 36.3: Formation of maltose from condensation of two glucose molecule.