The chapter discusses the dynamics of free-surface flows, particularly the spontaneous breakup of surface-tension-driven flows into drops. The focus is on the nonlinear behavior near the singular point where a drop separates, which has gained attention due to recent experiments and technological applications. The author reviews the theoretical development and experimental work, highlighting the universal scaling laws governing the separation singularity. The Navier-Stokes equation is shown to be uniquely continued through the singularity, and the dynamics are governed by one-dimensional equations. The chapter covers experiments with jets, dripping faucets, and liquid bridges, as well as simulations of inviscid, irrotational flow and Stokes flow. It also discusses the linear stability theory and the one-dimensional approximations used to describe the nonlinear dynamics. The universal self-similar solution leading up to breakup is detailed, and the dynamics away from breakup are explored, including the behavior at high and low viscosities. The chapter concludes with a discussion of related problems, such as two-fluid systems and electrically driven jets.The chapter discusses the dynamics of free-surface flows, particularly the spontaneous breakup of surface-tension-driven flows into drops. The focus is on the nonlinear behavior near the singular point where a drop separates, which has gained attention due to recent experiments and technological applications. The author reviews the theoretical development and experimental work, highlighting the universal scaling laws governing the separation singularity. The Navier-Stokes equation is shown to be uniquely continued through the singularity, and the dynamics are governed by one-dimensional equations. The chapter covers experiments with jets, dripping faucets, and liquid bridges, as well as simulations of inviscid, irrotational flow and Stokes flow. It also discusses the linear stability theory and the one-dimensional approximations used to describe the nonlinear dynamics. The universal self-similar solution leading up to breakup is detailed, and the dynamics away from breakup are explored, including the behavior at high and low viscosities. The chapter concludes with a discussion of related problems, such as two-fluid systems and electrically driven jets.