Sonography addresses a variety of concerns, such as patient safety and comfort, cost-effectiveness, time to complete a procedure, and success rates associated with invasive anesthesia procedures. Ultrasound guidance is commonly being used for the placement of nerve blocks, placement of peripheral and central lines, and arterial catheterization. Recently, it has been applied to preprocedural and imaged-guided spinal and epidural placement. The general terms and application of ultrasound to the practice of anesthesia are discussed in this article, as well as the general principles and the interpretation of basic images. Common procedures that include its use are also reviewed.