Kidney stones are hard deposits made of minerals and salts that form inside the kidneys. They develop when urine becomes concentrated, allowing minerals to crystallize and stick together.Types: Most are calcium stones, but others include struvite (infection-related), uric acid, and cystine stones.Symptoms: Often cause severe pain (renal colic) in the back/side, radiating to the groin, along with blood in urine, nausea, vomiting, and frequent urination. Small stones may pass unnoticed.Diagnosis: Involves urine tests, blood tests, and imaging (e.g., CT scan) to locate and identify the stone.