Kidney stones are hard mineral and salt deposits that form in the kidneys. They can vary in size, from tiny grains to larger stones, and may cause severe pain when passing through the urinary tract. Common types include calcium stones, struvite stones, uric acid stones, and cystine stones. Symptoms of kidney stones can include sharp pain in the back or side, blood in urine, and frequent urination. Treatment options range from drinking plenty of water to help pass the stones, to medications, and in some cases, surgical procedures may be necessary to remove larger stones.