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switch is a network connection device. It typically has four or more ports that can be connected to networked devices (most commonly ethernet devices).

All of the ports in a switch are equal.

The function of a switch is to receive data on any port and then send that data to the port corresponding to its intended destination.

Switches “learn” what ports correspond to specific destinations by examining the data being sent across its connections.

For example, if machine “A”, connected to the switch on port #3, sends data through the switch, then the switch has learned that machine “A” is connected to port #3. Subsequent data that the switch receives destined for machine “A” need only be sent down port #3, and no other port.

Contrast the behavior with that of a hub,which does not learn, but simply sends every packet of data that it receives to all available ports.

Related on Ask Leo!:

What’s the difference between a Hub, a Switch and a Router?

switch (Wikipedia)

In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type of switch is an electromechanical device consisting of one or more sets of movable electrical contacts connected to external circuits. When a pair of contacts is touching current can pass between them, while when the contacts are separated no current can flow.

Switches are made in many different configurations; they may have multiple sets of contacts controlled by the same knob or actuator, and the contacts may operate simultaneously, sequentially, or alternately. A switch may be operated manually, for example, a light switch or a keyboard button, or may function as a sensing element to sense the position of a machine part, liquid level, pressure, or temperature, such as a thermostat. Many specialized forms exist, such as the toggle switch, rotary switch, mercury switch, push-button switch, reversing switch, relay, and circuit breaker. A common use is control of lighting, where multiple switches may be wired into one circuit to allow convenient control of light fixtures. Switches in high-powered circuits must have special construction to prevent destructive arcing when they are opened.

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