Spinal anaesthesia is a widely used regional technique that provides adequate anaesthesia and analgesia for lower abdominal, pelvic, and lower limb surgeries. It involves the intrathecal injection of local anaesthetic into the cerebrospinal fluid (CSF) within the subarachnoid space, leading to differential neural blockade. The blockade follows a sequence affecting preganglionic sympathetic fibres, sensory, and motor nerves. Benefits include reduced postoperative pain, reduced need for airway manipulation, and decreased risk of venous thromboembolism. Common complications include hypotension, post-dural puncture headache (PDPH), transient neurological symptoms (TNS), and, rarely, spinal haematoma or infection. Ultrasound guidance enhances accuracy and safety in difficult cases.