Phacoemulsification, the use of a vibrating ultrasonic handpiece to break apart cataracts, is now the mainstay of cataract surgery in developed countries due to its smaller, and therefore less invasive, incisions. The ultrasonic handpiece breaks apart the cataract, after which an aspiration system sucks out the debris while an irrigation system cools the handpiece and provides fluid inflow. Combined with manual disassembly (i.e., chopping), there are many variations of phacoemulsification. Most surgeons start by learning the classic divide-and-conquer technique discussed in this chapter (Hausheer JR, ed. Basic techniques of ophthalmic surgery, 3rd ed. American Academy of Ophthalmology, 2019).