Gallstones?

Yesterday I went to the emergency room to find out I had kidney stones. I also found out I have 12-15 gallstones and need to have my gallbladder taken out! What are gallstones??Gallstones?
Gallstones form when liquid stored in the gallbladder hardens into pieces of stone-like material. The liquid, called bile, is used to help the body digest fats. Bile is made in the liver, then stored in the gallbladder until the body needs to digest fat. At that time, the gallbladder contracts and pushes the bile into a tube—called the common bile duct—that carries it to the small intestine, where it helps with digestion.
Bile contains water, cholesterol, fats, bile salts, proteins, and bilirubin. Bile salts break up fat, and bilirubin gives bile and stool a yellowish color. If the liquid bile contains too much cholesterol, bile salts, or bilirubin, under certain conditions it can harden into stones.
The two types of gallstones are cholesterol stones and pigment stones. Cholesterol stones are usually yellow-green and are made primarily of hardened cholesterol. They account for about 80 percent of gallstones. Pigment stones are small, dark stones made of bilirubin. Gallstones can be as small as a grain of sand or as large as a golf ball. The gallbladder can develop just one large stone, hundreds of tiny stones, or almost any combination.
gall stones are the stones formed in the gall bladder due to the more extraction of calcium