Fine-needle aspiration biopsy (FNAB) is a medical procedure used to collect cells from a lump or mass in the body. A thin, hollow needle is inserted into the area of concern, and a small sample of tissue is extracted. This technique is often used to evaluate suspicious growths, such as those found in the breast, thyroid, or lymph nodes. The collected cells are then examined under a microscope by a pathologist to determine if they are cancerous or benign. FNAB is minimally invasive, usually performed on an outpatient basis, and has a low risk of complications, making it a valuable tool in diagnosing various conditions.