A biopsy is a medical procedure involving the removal of a small piece of tissue from a living organism for medical analysis. It is most commonly used to diagnose diseases, especially those of internal organs such as the liver, kidney, lungs, and heart. In some cases, it may be used to determine the cause of a medical condition or to monitor the effects of a particular treatment. The biopsy is performed under the supervision of a medical professional such as a physician or surgeon. The tissue sample is removed with a thin needle or scalpel during the procedure and then examined under a microscope. The tissue sample may be examined in a laboratory to identify any abnormalities or infections present in the tissue depending on the type of biopsy being performed.