Jets refer to narrow, high-speed streams of fluid or particles that are propelled through a confined space. They are commonly encountered in various engineering and scientific fields, such as fluid dynamics, aerospace engineering, and particle physics. Jets can be produced through a variety of methods, including gas combustion, fluid injection, and particle acceleration. Research in the area of jets often focuses on understanding their behavior, dynamics, and interactions with surrounding environments, as well as developing technologies and applications that utilize jets for propulsion, mixing, and manipulation of materials.