Junction

A junction is a place where two or more things come together, such as roads, wires, or streams. In generic terms, it is a meeting point that connects paths or circuits, allowing transfer or distribution of traffic, energy, or information. The word derives from Latin iunctus meaning joined.

In road networks, junctions are points where routes intersect, merge, or diverge. They range from simple crossroads to grade-separated interchanges. Common designs include traffic-signal controlled intersections, roundabouts, diamonds, cloverleaf, and stack interchanges. Junctions are engineered for safety and efficiency, with signaling, turning lanes, and pedestrian facilities.

In electrical engineering, a junction is a point where conductors join. A junction box houses electrical connections. A p-n junction is a boundary between p-type and n-type material used in diodes and transistors; junctions are fundamental to semiconductor devices.

In computing and data management, a junction can refer to a file-system link that makes a directory appear in another location; Windows uses junction points, while Unix-like systems use symbolic links. In databases a junction table (link table) implements a many-to-many relationship.

In biology, cellular junctions connect adjacent cells and coordinate tissue structure and signaling; examples include tight junctions, gap junctions, and desmosomes.