How do two monosaccharides combine to form a disaccharide?

A monosaccharide is made of a 6-carbon cyclic ring. 5 out of the 6 form part of the ring while the other carbon acts as a side group of the 5' carbon in the ring. When forming a disaccharide with the next monosaccharide, the OH of the 1' C of one monomer undergoes a condensation reaction with the OH of the 5' C of the next monomer. This results in the formation of a glycosidic bond and the loss of a water molecule.