Capillary flow refers to the movement of fluids in small channels or capillaries, typically with diameters on the order of micrometers. This phenomenon is governed by surface tension, viscosity, and the geometry of the channels. Capillary flow has applications in various fields including microfluidics, biology, medicine, and engineering. Researchers study capillary flow to understand and control the transport of fluids in small-scale systems, as well as to develop new technologies and devices for liquid handling, drug delivery, and biological analysis. Techniques such as capillary electrophoresis, paper microfluidics, and digital microfluidics are used to investigate and manipulate capillary flow in different contexts.