Sugars are chains of carbon with -OH or alcohol groups hang off each carbon. When two sugars join, the -OH groups of two sugars merge. One sugar loses the -H off the -OH, and the other loses the -OH, which joins the -H (or an equivalent H) to become HOH, better known as water. The sugars can then be joined by carbons being linked to the same O witch is also called an ether bond.
