Components of an electrical circuit are electrically connected if an electric current can run between them through an electrical conductor. An electrical connector is an electromechanical device used to create an electrical connection between parts of an electrical circuit, or between different electrical circuits, thereby joining them into a larger circuit.
This rear panel of an integrated amplifier features a variety of electrical connectors
Connectors on the back of a 2018 computer
NMEA 2000 cabling using M12 connectors
A 4-pin Mini-DIN S-Video cable, with notches and a rectangular alignment pin
In the seven-layer OSI model of computer networking, the physical layer or layer 1 is the first and lowest layer: the layer most closely associated with the physical connection between devices. The physical layer provides an electrical, mechanical, and procedural interface to the transmission medium. The shapes and properties of the electrical connectors, the frequencies to transmit on, the line code to use and similar low-level parameters, are specified by the physical layer.
RTL8201 Ethernet PHY chip
Micrel KS8721CL – 3.3 V single power supply 10/100BASE-TX/FX MII physical layer transceiver